Reply to the foregoing.
Your correspondent G. H. says T. G. denies the possibility of Eels breeding in fresh water. This is rather too strong. I don't deny thepossibilityof Eels being bred in fresh water, I only deny theprobability. The expression I used was that I did not believe they were bred in fresh water at all, and I distinctly stated that my not having seen these things (Eel spawn, &c.), did not prove that other people had not done so. But to the question. G. H. says that he has caught them of all sizes, from the thickness of his little finger to five pounds weight. No doubt he may have done so, but did he catch them of the thickness of a crow's quill, and three inches long? because that is the size at which they usually ascend rivers. He says his pond does not communicate with any river. Is there no escape of water from it? I mean, is the evaporation from its surface equal to the supply of water? If not, where does the surplus go to? Does it not directly or indirectly flow into a river or the sea? I am the more inclined to think that this is the case, because G. H. says he caught a hundredweight at a time from a box which the water flows through at the bottom of the sluice-board. This is exceedingly like what is done here and elsewhere from July to the end of November, when the Eels are on their downward migration. Will G. H. be kind enough to say whether he does not catch his about the same time? will he also say whether the Eels he catches are not Silver Eels? and will he also state whether he does not catch them principally after heavy rains have increased the flow of water out of the pond? If he answers these questions in the affirmative, I shall still think I am right, and request him to keep a sharp look-out after rains in May and June, when I think he would probably see the grigs passing through his box into the pond. If, on the other hand, there is no escape of water from the pond at any time, I must admit that I am wrong, but at present I don't know how to reconcile the impounding the water so completely with what he says about the flow of the water through the box at the bottom of the sill. Where does the water flow to, and for what is this sill?
G. H. replied as follows.
T. G. asks if I have caught Eels of the size of a crow's quill. I have caught them of the size of a tobacco-pipe, and from three to four inches in length.
Our surplus water flows indirectly into the river Nene from our sluice. It supplies some stews where we have been in the habit of keeping reserve fish, and passing over several waterfalls, it enters into a ditch which is about three-quarters of a mile long, and then reaches the river I have just named.
The greatest take of Eels I have had was on the 23rd of December, but the time of the year is of little consequence with us, provided the water is thick and muddy and the weather rather warm, which, of course, only occurs during very heavy rains. If I were to draw all the water out of the pond when in a clear state, I should not catch a fish. The variety is the Silver Eel. Our pond is upwards of fifty miles from the sea; therefore how is it that those little Eels had got no larger during their long journey, interrupted as it is by numerous and almost insurmountable obstacles, before they could reach the little ditch, three- quarters of a mile long, that would conduct them to our pond? And, last of all, after this long and tedious journey, within a hundred yards of their destination they would have to climb four waterfalls and a perpendicular sluice-board. It appears to me they should have grown much larger than a common tobacco-pipe and longer than three or four inches in that time, but I will leave this point for T. G. to explain.—G. H.,Finedon Hall.
Reply to the foregoing.
Many thanks to G. H. for his second letter on this subject. It appears to me that we think very much alike about Eels.
He says his pond is fifty miles from the sea; "therefore, how is it that these little Eels get no larger in their long and tedious journey? interrupted as it is by numerous and almost insurmountable obstacles, before they could reach the little ditch, three-quarters of a mile long, which would conduct them to our pond? and last of all, after this long and tedious journey, within a hundred yards of their destination, they would have to climb four waterfalls and a perpendicular sluice-board. It appears to me they should have grown much larger than a common tobacco-pipe during that time; but I will leave that point to T. G. to explain."
This is so fairly put, that I will tell what I have seen, hoping that this will be a sufficient explanation.
In June, 1850, I chanced to go down to the bank of the Ribble, and there I saw a column of small Eels steadily making their way up the stream. I should suppose there might be fifty in every lineal yard, for they kept pretty close to the bank, apparently because they met with less resistance from the stream, and without pretending to accuracy I supposed they travelled at the rate of a mile an hour. This was about five o'clock in the afternoon, and I went to look for them about nine in the evening—they were still going in one unbroken column. How long they had been going when I first saw them, and how long they continued to go after my second visit, I don't know, but many thousands—perhaps millions—must have passed that day. At this rate (of a mile an hour) they would have required little more than two days to reach G. H.'s pond, fifty miles from the sea; but he says they had to pass over three or four waterfalls and a perpendicular sluice-board. If these waterfalls and the sluice-board were covered with moss, they would climb them as readily as a cat does a ladder. I have seen them in swarms at a perpendicular weir here, winding their way through the damp moss with which the stones are covered; but this was not all: where there was no moss, the little things seemed to have the power of adhering to the perpendicular face of the stones, like so many snails. I must not omit to remark, that although they seemed to choose the margin of the stream for the sake of easier travelling, yet they took care to keep in the stream, as I had a nice opportunity of observing.
At the point where I first saw them, the tail goit of a water- wheel had its junction with the river, but being Sunday there was no current there—not a single Eel took its course up the goit, although the water was deeper there than where they went. The water being low and perfectly clear, I could trace their course both above and below the place where I stood without any difficulty.
If we allowed that they travelled a mile in the hour, and that the obstructions of the waterfalls and sluice-board took as long to get over as all the rest of the journey, they would be able to reach G. H.'s pond in four days from the sea; and from what I have seen of their ability to surmount such obstructions, I am quite convinced that they would travel that distance in the time. But say they were a week—they would not grow much in that time, particularly if they had been travelling without food the whole of the distance, and that they must have done so, is proved to my mind by their keeping in column; for if they had dispersed to seek for food, by what contrivance were they marshalled into line again, to enable them to proceed? Now the place I saw them is forty miles from the sea, although not that distance from salt- water. T. says it is no proof that Eels are bred in fresh water because they may be found in ponds having no connection with a river—the proof required isab ovo. If we wait for this proof I fear we will have to wait for some time, for I fancy that no one but Mr. Boccius ever saw the ova of Eels, and he will not condescend to enlighten us on the subject. At the same time I admit that finding them there is no proof that they were bred there, inasmuch as I have myself stocked such ponds for my friends, and what I have done may be done by others.
T. says further there is also room for inquiry into another curious subject—do Eels return to fresh water after having gone to the sea for spawning? In reply to this, I can only say, that no trace of such a migration is ever seen here, and I think if it existed at all, I should have observed it, for the following reasons.
The Ribble here supplies a large mill, the water-wheels of which are 150 horse-power; therefore, when they are at work in the daytime, the whole force of the river is often passing through the mill-lead (goit) and the bed of the river between the weir, and the tail goit in such times is left dry, except in a few pools. If there was a shoal of Eels between these two points it would have been seen at one time or another, and this has never happened, so far as I know. It may be said that they migrate singly, but they don't do so in their first migration, and, so far as I am aware, it is not the habit of any animal to do so. Herrings, Pilchards, Smelts, Flounders, Sturgeon, Bisons, Antelopes, Woodcocks, Swallows, Fieldfares, Locusts, and even Butterflies congregate together previous to migration.
NOTE.—The last paragraph requires some modification, as I have since proved that Eels migrate singly when going to the sea, as I have had occasion to know in a hundred cases when watching my Eel- trap, where every Eel may be seen as it descends into the trap.
On the same subject.
I [Jeremiah Garnett, brother of the writer, and editor of the "Manchester Guardian,"] having noticed the communications on this subject which have recently appeared in your columns, am desirous of mentioning a fact which appears to me to throw some light upon the localities in which Eels are bred, though it leaves the question of the mode of generation precisely where it stood before.
Like your correspondent T. G., I have many times seen columns of small Eels ascending the Ribble and other rivers in the months of May and June, at considerable distances from the sea, but only on one occasion have I seen them under circumstances which evidently brought them near the place of their nativity.
I happened to be attending the Lancaster Spring Assizes in the month of March in the year 1826, and learning that there was a remarkably high tide in the estuary of the Lune, I walked down to the riverside about the time of high water, and found that the tide had covered the grass in many places; and as it began to ebb, I observed something moving in every small hollow which had been overflowed, and in which a little water had been left behind. On examination I found that the moving bodies were exceedingly diminutive Eels, rather less, to the best of my recollection, than three-quarters of an inch long, and almost transparent, but exhibiting in every respect the true form of the mature Eel. They had evidently followed the water to its extreme verge, where it could not have been more than an inch deep, and that they must have been very numerous was clear from the large numbers which were left behind and had perished—for that they did perish I found on the following day, when they were lying dead on the grass by hundreds. Some of your correspondents who reside in localities favourable for making observations on this subject may be induced to pay attention to it; the exact appearance may be ascertained, with probably other facts calculated to throw light on the obscure question of their generation.
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October, 1859.
The colonists of Australia, Tasmania, and New Zealand appear to wish for the introduction of Salmon and Trout into the rivers of these colonies, and one of them, Tasmania, is said to have offered the reward of L500 for the first pair of live Salmon which reaches that colony. If this is true it is a liberal offer, and one that is likely to induce various persons, both in England and France, to make the attempt.
I should be sorry to say anything to check so laudable an endeavour, but I greatly fear that Van Diemen's Land (to say nothing of the Australian colonies) is too near the tropics to offer a reasonable chance of success. I think it is practicable to take these fish there (or at least fertilized ova), but I don't think they would live and thrive in the rivers of that colony. Never having been there, I can, of course, only reason from European experience, but the best inquiries I can make lead me to suppose that there are no Salmon in France (south of Brittany), Spain, or any of the countries washed by the Mediterranean Sea; and in America (although I confess I am not so well informed on that country) I have never heard of Salmon being seen to the south of the tributaries of the St. Lawrence. Supposing this to be so, I think that we may fairly infer that if Salmon are not found south of a certain latitude in Europe and America, it must be that the climate of these southern countries is not congenial to the habits of this fish. I believe, however, that the Trout lives and thrives much further south than the Salmon; for instance, it is found in the Pyrenees and in the lakes of Northern Italy (Lady M. W. Montagu). It is also found in Northern Turkey, and probably Albania also (Spencer); and therefore I think it is quite probable that it might live in Tasmania—that is, if the streams are never dried up and the rivers reduced to a number of water-holes, which appears to be the case in Australia. Should this be the case in Tasmania also, I doubt whether even Trout would thrive, for here in Lancashire I have known the Trout to die in great numbers from the heat, when, owing to the water-wheels of the mill diverting the river from its usual channel, there was no stream, but merely a series of detached pools or water-holes; and the Grayling seem to be more incommoded by heat than the Trout, and it was one of the diversions of my boyhood to wait until the wheels of my father's mill were stopped in the hot weather, and then go up the covered wheel-races in search of the Grayling that had gone there to get out of the sunshine. I used to catch them there in great numbers. However, this has nothing to do with the matter, except to suggest that although Grayling are very desirable fish to introduce into the colonies, I fear they would be too impatient of heat to thrive there. But my object in addressing you is to ask whether it is true that the legislature of Tasmania has offered the prize of L500 for the first pair of live Salmon taken there?
Secondly, whether they offer a prize for the introduction ofSalmon fry; and if so, what is the amount offered?
Thirdly, whether they offer a prize for the introduction of fertilized ova of Salmon or Trout, and what is the amount?
I ask these questions because I happen to know a good deal on such matters, and I have been applied to this day by James Birch, the head water-bailiff of our river (Ribble), to obtain some information for him on the subject, as he seems seriously bent on making the experiment, provided the reward be an adequate one; for, to be successful, it would involve the necessity of his making the voyage himself, and it would be a cruel thing to induce him to do so, and in the end to find that he was entitled to no reward.
I'll say this for him, that if he tries he will succeed, if success be possible; but his pecuniary resources are too limited for him to undertake such a risk.
I have reason to believe that he has been applied to by Ramsbottom to go to Tasmania, but this he declines to do under Ramsbottom's auspices. As he (R.) professes to be in communication with the authorities of Tasmania (or at all events with influential persons there) let him make the first attempt, and if he succeed, there will be no necessity to apply to me on the subject; but if he should fail—as I think he will—why, then the persons interested in the matter may, if they wish to try again, let me know their wishes and the amount of remuneration they mean to give.
I should certainly suggest that both Salmon and Salmon Trout (as well as the common Trout) should be included in their list of desiderata, and although for reasons previously given I have no great hopes of success with the two former, I think it quite probable that the common Trout would succeed better. Of course I know nothing of the fish already in the rivers of Tasmania; for aught I know there may be fish in all those rivers quite as voracious and destructive as the Pike are here. If this is the case, the chances of success would be materially lessened, as Trout and Salmon fry are rare in all rivers stocked with Pike. However, those who are making the attempt ought to know what they are about, and will, no doubt, have considered such obstacles, if there are any such in the way. Will you, therefore, be kind enough to answer the questions I have asked above, at your earliest convenience, and if your replies offer any inducement to Birch to make the attempt, I have no doubt that he will be quite ready to do so.
For various reasons he can only start from here in the autumn or winter, and he should, if he reaches Tasmania with either live fish or fertilized ova, have someone to render him prompt and cordial assistance to enable him to deposit the fish or ova, or fish and ova, in suitable places for spawning and hatching; and therefore if this letter be replied to, the answer ought to say to whom Birch should apply on his arrival in Tasmania.
It may be asked, who is the man who obtrudes his opinions on the colony unasked, and what can be his motives? As I am not aware that I know a single person in Tasmania, I cannot refer to anyone there; but I happen to know one or two gentlemen in Melbourne, and if you will take the trouble to refer there to Messrs. W. and B. Hick, or to W. Bailey, the corn merchant, they will be able to satisfy all inquiries.
If it be asked what I know of the habits of fish, and Salmon in particular, I beg to refer the inquirers to Loudon's "Magazine of Natural History" for 1834 (if there is a copy of that work in the colony), and they will there find two papers (signed "T.G.," Clitheroe) which will show that I then knew all that has since been proved by the elaborate experiments made at Perth by Ramsbottom, and moreover I taught Ramsbottom himself the art of propagating fish artificially.
I want no compensation: the honour of being the first man who succeeded in introducing these valuable fish into the colonies would be a sufficient reward to me. But with Birch the case is different: he is a working man, and L500 would be a fortune to him. On the other hand, he could not afford to come to Hobart Town from England at his own expense, as he has not the means.
Would the colony, if other attempts failed, be willing to pay Birch's passage out and home if he failed also, and would he receive the L500 if he succeeded?
By success I mean that he would either bring live fish or ova that would hatch into live fish. Either of these objects being accomplished, he ought, in my opinion, to receive the reward; for although he would attempt both, he would probably fail in the former.
Should he attempt this under my advice, I should not only send Salmon and Salmon Trout and their ova, but the common brown Trout and its ova also, for the reason previously given in this letter; and although I am by no means sanguine of success, on account of the temperature, the experiment is too important to be abandoned for a mere theoretical objection which may be erroneous.
I think New Zealand offers far greater chances of success. It is not only further removed from the tropics, but, if I am rightly informed, the streams are more abundant and constant than those of Australia and Tasmania—in fact, I believe it is as well watered as this country; and if the authorities there are as much alive to the importance of introducing these fish into their rivers, I would undertake to do this with much greater confidence of ultimate success than I should have if I undertook to introduce them into Tasmania or the sister colonies.
Some time since (it may be eighteen months or two years ago) there was a very intelligent correspondent of the "Field" newspaper, whosenom de plumewas the Maori one, "Wetariki no te wai Herekeke," or a similar one; and I having written something in the "Field" on this subject, the New Zealander asked for my address, which, for some private reason of his own, the Editor declined to give until so long a time had elapsed that Wetariki Herekeke had returned to the colony—this I learnt from an indirect source— otherwise I should have tried to induce him to undertake the experiment of introducing all the various species of the genus Salmo which are to be found in our rivers.
If the colonists of New Zealand wish to make the attempt, I shall be most happy to render them all the assistance in my power, and I know no one so qualified as Birch to undertake the management of such an experiment; for he is exceedingly intelligent, has a perfect knowledge of the habits of both Trout and Salmon, and thoroughly understands the feeding of fish, both in their natural haunts and artificially, and would consequently be able to select suitable localities for conducting such an experiment to a successful issue.
NOTE.—No reply was given to this by the authorities of Tasmania, but a similar communication, addressed to the Governor of New Zealand, elicited a very polite reply from his secretary, in which he said that there were no funds available for such a purpose, but that the subject would be brought before the legislature on their assembling, and would no doubt meet with their favourable consideration; but the Maori troubles broke out immediately after, and I heard no more about it.
* * * * *
CLITHEROE,October 14th, 1859.
To the Editor of the "Field."
In the "Field" of some weeks since, it was stated that the colonists of Tasmania were offering a large reward for the introduction of live Salmon, Salmon fry, or the fertilized ova of Salmon.
Will you have the kindness to say what was the amount offered? who were the parties who made themselves responsible for the payment? and what time did they give within which they would pay for a successful attempt?
I am the more anxious to have this information, because I have been applied to for advice by an exceedingly likely person, as the reward (L500) which he understood to be offered is to him so tempting a sum, that he would need very little encouragement to undertake the management of the experiment; and from what I know of him I will venture to assert that he will succeed, if success be practicable.
But before I speak confidently of success, I would like a little more information, and will thank any of your readers who are able to do so, to give me replies to the following questions:—
Are there any Salmon in the rivers of Spain, or in France, south of the Loire, or even in that river? If not, why not?
Are there any Salmon in North America, in any river (not a tributary of the St. Lawrence), south of that river? If there are, what rivers in the States contain Salmon.
Do any of the rivers on the west coast of America below the latitude of 40 degrees N. contain Salmon?
Do any of the rivers of China (not Chinese Tartary) containSalmon?
If I am right in supposing that the rivers I have pointed out have no Salmon in them, is it not exceedingly probable that the high temperature of these southern countries is unsuited to the habits and uncongenial to the health of these fish? Or how is it when they are on the same seaboard further north, they don't ascend these rivers, unless there are some such objections to their doing so? And if these objections really exist, then do they not equally exist in the rivers of Australia and Tasmania?
But there may be other objections equally fatal: there may be fish in their rivers as voracious and destructive as our Pike; there may be Sharks and other fish in their seas and estuaries, which would snap up every Salmon that entered them. There may be Seals, Porpoises, Albatrosses, Man-of-War birds, and Cormorants, as well as fifty other nameless enemies, all combining their efforts to defeat so desirable a consummation; and, after all, there may be no one willing to make himself responsible for a repayment of the necessary expenses, for corporations and public bodies are proverbially untrustworthy.
Yet, notwithstanding all these doubts of success, I think the experiment ought to be made; for its success would confer so great a boon on the colony in which it was made, that they (the colonists) ought to incur considerable risk and outlay for the chance of success, however small. I don't think there will be much difficulty in carrying fertilized ova there, but when hatched I fear they would not thrive.
I think New Zealand offers far better chances of success: it is further from the tropics, it abounds in suitable rivers, the climate and temperature are more like England, and I believe the rivers never degenerate into mere water-holes, as they seem to do in Australia; and I think the residents of that colony ought to make a vigorous attempt to introduce Salmon, Salmon Trout, and the common brown Trout into their rivers immediately; and I should be delighted to render all the assistance in my power to accomplish so desirable an object.
* * * * *
Anchor Frosts.
A correspondent of the "Magazine of Natural History," in endeavouring to explain the causes why water freezes at the bottom in rapid streams, says this unusual phenomenon may be rationally accounted for by anyone who has attended to it; that the streams in which anchor frosts occur generally are those which contain water of different temperatures—viz., surface-drainage and land springs and main springs, the first being always colder than the latter, in winter these never being less than 40 degrees, even in severe frosts.
These colder globules being first frozen, float on the surface of the water individually, being prevented from coalescing by the intermediate main-spring-water, and where the water passes in a shallow stream over the pebbles the crystals are intercepted by the interstices of the stones, and then become heaped together in thick beds.
The fact of the crystals of ice (which are specifically lighter than the water) sinking below the surface, is a circumstance requiring explanation. They do not sink from their specific gravity, but in the commotion of the current they are occasionally submerged, and while so are stopped by any obstruction, when they commence and compose the aggregation.
Thinking this was an erroneous view of the matter, I replied as follows:—
J. M., in his remarks on anchor frosts, appears to me to have fallen into several errors in endeavouring to account for them (they are called bottom frosts in Yorkshire); for, admitting that main springs are of the temperature stated (40 degrees) when they issue from the earth, I am by no means prepared to believe that they keep that temperature long, or that the water issuing from them does not mingle intimately and immediately with the water of the river into which it flows; especially in the situations where anchor frosts are most common, which are rough and rapid streams.
From J. M.'s statement it would appear that globules of water of different temperatures mix together without the one imparting its excess of caloric to the other, which is contrary to the experience of everyone; it is true, that in still places there will be different temperatures in the same body of water, but it is not owing to the main springs of which J. M. speaks, but to the peculiar way in which water is affected by cold. It is well known that water increases in density down to 40 degrees, below which temperature it begins to expand, and this expansion continues until it reaches the freezing-point, so that in severe frosts there will be strata of different temperatures from 32 degrees to 40 degrees. Again, he says that "the crystals of ice are intercepted by the interstices of the stones, and then become heaped together in thick beds;" but if my observations are correct, these depositions begin first round the large stones, which are not likely to stop small spiculae any more than are the water-gates of mills, where, he says, the accumulations also take place.
Anchor frosts are most common in the rapid streams occurring below deeps in rivers, and I have seen a weir on the river Wharfe which had a wall of ice four feet high formed upon it in a single night by a sharp north wind. In my opinion a sufficient explanation of this freezing at the bottom of rivers is to be found in the fact that water when kept still may be cooled down below the freezing- point without being congealed; but if the vessel in which it is kept be shaken, a portion of it will be converted into a porous, spongy ice, and the temperature immediately rises to 32 degrees. In the deeps of rivers the same cooling below the freezing-point takes place without congelation, but as soon as this water reaches the stream below, the agitation immediately converts a portion of it into ice, which collects round the large stones at the bottom in the same way that crystallization commences in a solution of salt or sugar around a piece of thread or other substance which may be suspended in it. If a severe frost is followed by a bright day, thousands of these detached pieces of spongy ice may be seen rising from the stones which have served as nuclei for them; which proves that the detention of them is not merely mechanical, but that precipitation (if I may be allowed to call it so) takes place in the first instance, the stone serving as a nucleus, and that this adhesion is destroyed by the action of the sun's rays.
I have never seen any attempt to explain the phenomenon of bottom- frosts before this of J. M.'s, and I am not philosopher enough to speak positively on the subject; but the above is the way in which I have always endeavoured to account for it. Perhaps some of your scientific readers may be able to give much better reasons for it than have been offered either by J. M. or myself. (January 17th, 1832.)
Another writer (J. Carr, of Alnwick,) says that anchor frosts are merely long and severe ones where long masses of ice are frozen to the stones at the bottom of rapid streams, and this is simply owing to these stones acquiring a degree of cold far below the freezing-point, and the water in contact with them freezing and spreading into large sheets of ice, which are sometimes torn up and carry away the gravel adhering to the under surface.
Thinking that this was an error, I again wrote to the "Magazine ofNatural History" as below:—
I perceive that others beside myself have endeavoured to account for anchor frosts. Mr. Carr says they never occur except in long and severe frosts, and that the adhesion of the ice to the stones at the bottom is owing to their acquiring a degree of cold far below the freezing-point. He is in error when he says they never occur except in long-continued frosts, as the walls of ice which are sometimes raised on the crowns of weirs are invariably (so far as my observations have extended) deposited therebeforethe water in the reservoir above is frozen over, which proves that the frost has not been of long continuance, although it may have been severe. As to what he says about the stones acquiring a degree of cold far below the freezing-point, and imparting that coldness to the water, I would just ask how it is that a stone at the bottom of a river acquires this excess of cold, and if it is not more probable that the stones impart warmth to the surrounding water? I can easily conceive how the stones may, by the action of the sun's rays upon them, warm the surrounding water; but I do not see how they can impart cold, or, in other words, how their temperature can be reduced below that of the water by which they are surrounded. Stones certainly impart warmth to the water they are in, in bright weather, as the rays of the sun do not give much warmth in passing through any transparent medium; but on coming in contact with any opaque bodies, the heat is absorbed or reflected as the case may be, and in this way transparent media such as air and water acquire a warmth by contact which they would not otherwise possess. Thus, if an anchor frost is followed by a bright day, the rays of the sun impart so much warmth to the stones at the bottom of the river as is sufficient to liberate the ice from them, and on such days thousands of pieces of ice may be seen rising from the bottom and floating down the streams.
Since my former observations were written I have had the satisfaction of finding my views on the subject confirmed by a very eminent chemist, [15] and if the discussions in your Magazine were to be settled by authority, and not by argument (which I trust will never be the case), he is one to whom many would be inclined to appeal, and to whom few would refuse to submit. (May 2nd, 1832.)
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To the Editor of the "Agricultural Gazette."
In a leading article of the 10th of January, 1852, after an account of the effects produced on water by radiation and the protection afforded to plants by the ice with which ponds are covered in winter, you go on to say that there are some circumstances under which water-plants suffer greatly, and from a singular cause, but one which when looked into is sufficiently simple and intelligible. As you do not appear to have hit upon the true reason, allow me to quote a little further, and then give my reason for this singular effect.
You say that on a very fine but still night, water is cooled less rapidly than the earth: under such circumstances the bottom of the pond cools more rapidly than the surface, the plants become colder—in fact, some degrees below the freezing-point, &c. &c.
I submit that such reasons are inadmissible, for there would be an immediate upward current, which, as water is such an excellent conductor of heat, would immediately equalize the temperature of all the water above 40 degrees Fahrenheit, and stratified (if I may use the expression) above the water of this temperature there would be another layer of water of equal but gradually decreasing temperature until it fell below 32 degrees Fahrenheit.
The explanation I offer is this. It is well known that if water is kept perfectly still it may be cooled down considerably, or at least some degrees below 32 degrees, without freezing; but the moment it is shaken a portion of it is converted into a spongy, porous ice, and the temperature rises to 32 degrees.
What may be the case in the rivers of the South of England I do not know, but in the rapid streams of the North this process may be seen on a very extensive scale in severe frosts. The water in the still pools (before they are frozen over) is cooled down to below 32 degrees, and so soon as this cooled water reaches the next stream, precipitation (if I may so call it) takes place, and the spongy ice lays hold of every projecting pebble, which serves as a nucleus in the same way as threads and bits of stick serve in the crystallization of salts. After a severe frost, when followed by bright sunshine the next morning, I have seen thousands of these bits of spongy ice rising from the stones to which they had been attached to the surface of the water. I have seen after long- continued frost the course of a stream completely altered by this bottom-ice (as it is called here), and I have also seen a weir with a wall of ice on it three feet high (raised in a single night) by the same cause. Now apply this to the bottom-ice in ponds (which however I must confess I never saw). The night being calm, the water gets cool below 32 degrees, but then a breeze springing up the water becomes agitated, precipitation takes place, and the plants serving as nuclei become immediately clothed with this spongy ice, and the sun shining next morning imparts so much warmth to the plants that the ice thaws which is in contact with them, and rises to the surface. Of course if the sun does not shine next morning, and the frost continues, the plants may be clothed with ice for a long time.
To the foregoing the Editor of the "Agricultural Gazette" replied as follows:—
We cannot admit the soundness of our correspondent's explanation of the formation of bottom-ice or groundgore. We are well acquainted with the statements of Arago and other writers as to the cause of this curious phenomenon, and after a careful consideration of the subject believe that it is due to radiation and not to any other cause. Bottom-ice has been observed in ponds on perfectly still nights when there was no breeze to agitate the surface of the water.
The waters in the pools between the rapids of rivers can hardly ever be still enough for the water to fall below the freezing- point and yet remain fluid; the temperature of water in such situations is not below 33 degrees.
The following was my rejoinder:—
You say at the end of remarks about bottom-ice that you cannot admit the soundness of my explanation, and that you are well aware of what is said by Arago and others on this curious phenomenon, and that bottom-ice has been observed in ponds when there was no breeze, and that the water in pools between the rapids of weirs can hardly ever be still enough to fall below the freezing-point, and yet remain fluid.
I was not aware before seeing your remarks that either Arago or any other philosopher had ever written about bottom-ice, and even now I do not know what are their opinions on the subject, and if the discussions in your paper are to be settled by authority and not by argument, I can only make my bow and withdraw; but if it meets your views to allow your correspondents to state their opinions temperately, and support them by such arguments as occur to them, I do not yet feel inclined to give up my notions about bottom-ice. Will you allow me to ask whether you ever personally saw ice at the bottom of a pond when there was none on the surface? and if so, under what circumstances? I have heard of such an occurrence, but never witnessed it, and feel inclined to doubt the fact unless you will vouch for it; for it appears to me that the moment the water at the bottom falls below 40 degrees it will begin to rise to the surface, and it is so excellent a conductor that it will instantly equalize the temperature of the mud at the bottom with that of its own temperature.
I am neither chemist nor meteorologist, and therefore I am not able to say much about radiation; but my idea of it is, that its effects in water would be much greater in still pools than in rapid streams, and that, therefore, if radiation was the cause of bottom-ice, there ought to be more of it in the pools than in the rapid streams. But the contrary is the fact, for after a severe night's frost, I can frequently find the streams filled with this bottom-ice, when none can be observed in the pools.
Again, can the fact of the weir which had a wall of this bottom- ice three feet high in a single night, be accounted for by radiation? It appears to me to be very easily accounted for by supposing that the water in the deep above was so quietly cooled down as to retain its fluidity until the shaking it got on flowing over the weir suddenly produced congelation. I think that radiation would not go on at the crown of the weir alone.
Why do you think that the water in pools is never still enough to allow it to get below 32 degrees without freezing on still clear nights? In long deep pools, where the body of the water is perhaps a hundred times as great as the current flowing into it, the motion is so extremely slow that I cannot for a moment doubt that it gets below 32 degrees without congelation, but when it arrives at a rapid, this ice is immediately formed.
The Editor closed the discussion at this point by saying that the subject was not of sufficient agricultural importance to be continued further.
The following is my brother Richard Garnett's [16] account of his observations on bottom-frosts. (The paper was written in 1818, and published in the "Journal of the Royal Institution.")
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The phenomenon of the production of ice at the bottoms of rivers has been repeatedly noticed, but I am not aware that any satisfactory solution of the cause has hitherto been given. In Nicholson's "Dictionary of Chemistry," several different hypotheses are enumerated, which I shall not stop now to examine, since it may be safely asserted that they neither accord with the established principles of chemistry, nor with the facts for which they endeavour to account. The most recent theory with which I am acquainted is that of Mr. A. Knight, who in a paper lately published in the "Philosophical Transactions," seems to consider the particles of ice as originally formed at the surface, and afterwards absorbed by the eddies of streams to the bottom. He states, in support of this idea, that he did not observe any similar phenomenon in still water. I shall advert to this hypothesis in the sequel, and at present it may suffice to remark of it and all others which I have hitherto seen, that supposing any of them to be correct, the same effects ought regularly to be produced whenever the atmosphere is at a similar temperature, or in other words, that whenever the frost is so intense as materially to affect the water of a river, we may then expect to find ice at the bottom. Now this is certainly not the case, since the appearance we are treating of never occurs but under peculiaratmosphericalcircumstances, and rivers are frequently frozen over, and remain so for a length of time without a particle of ice being visible at the bottom of their streams. I do not now profess to have developed this mystery, but merely intend to state the circumstances under which the phenomenon takes place, as well as a few particulars connected with it, which are perhaps not generally known, and which may hereafter be serviceable as data for investigating the cause.
It is well known to meteorologists that a severe frost in winter does not always commence in a uniform manner. Sometimes it begins with a gentle wind from the E. or N.E., and is at first comparatively mild in its operations, but afterwards gradually increases in intensity. Frosts of this kind are generally more lasting than others, and during such, I have not observed that any ice is generated at the bottoms of streams; though the deep and still parts of rivers are often frozen over to a considerable extent. At other times, during the continuance of the violent south-westerly gales which are so prevalent in this country in the winter months, the wind frequently shifts on a sudden from S.W. to N.W., commonly about an hour before sunset, and blows with great impetuosity in the latter direction, attended with a severe frost, and sometimes with a heavy fall of snow. The effects of this frost, in places exposed to the wind, are extremely rapid, so as to render the ground impenetrably hard in about a couple of hours from its commencement. Situations that are not so much exposed seem comparatively little affected—at least, I have repeatedly observed that a small sheltered pond in a field was nearly free from ice, while the current of a large and rapid river at no great distance was nearly choked up by it. I believe that the phenomenon under consideration seldom occurs except during such frosts as these, and the following are the principal circumstances connected with it which I am able to state from my own observation.
It may here be premised that ice of this description is seldom seen adhering to anything beside rock, stone, or gravel, and that it is more abundantly produced in proportion to the greater magnitude and number of the stones composing the bed of the river, combined (as will be further noticed) with the velocity of the current. I have been informed by a friend that he has occasionally seen it attached to solid wooden piles at a considerable depth below the surface of the water, but I never saw or heard of any on earth, mud, or clay. It is not easy to ascertain the precise time at which the process begins to take place. It appears, however, almost invariably to commence during the first night of the frost, and probably within a few hours after sunset. On the ensuing morning the first thing which strikes an observer is an immense quantity of detached plates of ice floating down the stream. Mr. Knight naturally enough supposed these to have been formed at the surface by the influence of the freezing atmosphere, and afterwards absorbed by the current; but I think that a minute inspection would have led him to form a different conclusion— viz., that they are first formed in the bed of the river, and afterwards rise to the surface. It is true that none are to be seen in situations where there is no sensible current, and that they abound most in rough and rapid places; but on closely examining any stream of moderate velocity, yet smooth, equable, and free from all appearance of eddy or rippling, a great number of these plates of ice will be found adhering to the rock, stone, or gravel at the bottom. If they are watched with attention, they will be observed to rapidly increase in bulk, till at last, on account of their inferior specific gravity, aided, perhaps, by the action of the current, they detach themselves from the substances to which they first adhered, and rise to the surface of the water. The form of these pieces of ice is very irregular, depending in a great measure on the size and shape of the stones or other substances to which they were originally attached. Most of them seem to be of an oblong or circular figure; they are generally convex on the upper surface, and have a number of laminae and spiculae shooting from them in various directions, especially from their circumference. Sometimes when those floating pieces or plates meet with any obstruction in the channel of the river, they accumulate in such quantities as to cover the surface of the water, and become frozen together in one large sheet, but this kind of ice may be always readily distinguished from that produced in the usual way by the action of the cold air on the surface, which is smooth, transparent, and of an uniform texture; on the contrary, one of these conglomerated fields or sheets is opaque, uneven, full of asperities, and the form of each separate plate composing it may be distinctly traced. In this situation, they generally assume the shape of irregular polygons, with angles somewhat rounded; a form apparently caused by the lateral pressure of the contiguous pieces.
On the river Wharfe, near Otley, in the West Riding of Yorkshire, is a weir or milldam where this phenomenon is sometimes manifested in a striking manner. This structure is of hewn stone, forming a plane inclined at an angle of from 35 degrees to 50 degrees, fronting the north and extending from west to east, to the length of 250 or 300 yards. When one of the above-mentioned frosts occurs, the stone which composes the weir soon becomes incrusted with ice, which increases so rapidly in thickness as in a short time to impede the course of the stream, which falls over it in a tolerably uniform sheet, and with considerable velocity; at the same time, the wind blowing strongly from the north-west, contributes to repel the water and freeze such as adheres to the crest of the weir when its surface comes nearly in contact with the air. The consequence is that in a short time the current is entirely obstructed, and the superincumbent water forced to a higher level. But as the above-mentioned causes continue to act, the ice is also elevated by a perpetual aggregation of particles, till by a series of similar operations an icy mound or barrier is formed, so high as to force the water over the opposite bank, and thus produce an apparent inundation. But in a short time the accumulated weight of a great many thousand cubic feet of water presses so strongly against the barrier as to burst a passage through some weak part, through which the water escapes and subsides to its former level, leaving the singular appearance of a wall or rampart of ice three or four feet high, and about two feet in thickness, along the greatest part of the upper edge of the weir. The ice composing this barrier where it adheres to the stone, is of solid consistency, but the upper part consists of a multitude of thin laminae or layers resting upon each other in a confused manner, and at different degrees of inclination, their interstices being occupied by innumerable icy spiculae, diverging and crossing each other in all directions. The whole mass much resembles the white and porous ice which may be seen at the edge of a pond or small rill where the water has subsided during a frost.
It may be further observed that a frost of this kind is very limited in its duration, seldom lasting more than thirty-six or forty hours. On the morning of the second day after its commencement, a visible relaxation takes place in the temperature of the atmosphere. Usually before noon, the wind on a sudden shifts to the south-west, and a rapid thaw comes on, frequently attended with rain. What appears somewhat remarkable is, that during several hours after the commencement of the thaw, the production of ice at the bottom of rivers seems to go on without abatement, and upon examining a rapid stream, the stones over which it flows will be found at this period completely incrusted with the above description of icy plates. It seems evident from this that the bed of the river, which has been reduced below the freezing temperature, is not for some time affected by the change of the atmosphere. This may be in some measure illustrated by the well-known fact, that rain which falls upon a rock or stone wall, is frequently converted into ice, though the air and the ground are evidently in a state of thaw. Before the following morning, the ice of which we have been speaking generally disappears, being carried away by the current or dissolved by the thaw.
The last time that I remarked this phenomenon, was in a stream of the river Aire, near Bradford, in Yorkshire, on the 1st of January, 1814. This instance did not precisely accord with what I have stated to be the usual circumstances of the case, as the frost then had existed several days without any previous appearance of this kind; but there were several indications of approaching change of temperature, and the day following there was a partial thaw attended with rain, the wind having veered from north-west to south-west. This thaw, however, did not continue long, and was succeeded by a frost which surpassed all within my recollection in severity and duration. Yet during the whole of the period, though the thermometer often stood below 18 degrees Fahrenheit, and the estuary of the Tees several miles below Stockton, where the spring-tides rise from twelve to eighteen feet, was for two months frozen over, so as to allow the passage of a loaded waggon, I could never perceive a particle of ice adhering to the rock or gravel, in the bed of the small and rapid river Leven in Cleveland, where I then resided. This circumstance seems decisively to prove that the phenomenon does not merely depend on an intensity of cold.
I confess I am unable to frame any hypotheses respecting the above-mentioned facts which would not be liable to numerous and formidable objections. The immediate cause of the formation of the ice seems to be a rapid diminution of the temperature in the stone or gravel in the bed of the river, connected with the sudden changes in the state of the atmosphere, but it does not seem very easy to explain the precise nature of this connection.
We may easily conceive that by a sudden change from a state of thaw to an intense frost attended by a strong wind, the whole body of water in a river may become quickly cooled, and consequently diminish the temperature of the stone or gravel over which it flows; but to suppose that water which is not itself at freezing- point is capable of reducing the substances in contact with it by means of a continual application of successive particles so farbeneaththat temperature as in process of time to convert the contiguous water to ice, seems not to accord very well with the usually received theory of the equilibrium of caloric. However, the fact that the quantity of ice thus produced is always greater in proportion to the superior velocity of the stream, little or none being found where there is no sensible current, seems in some degree to countenance the above idea.
I cannot learn that any experiments have ever been instituted on this subject, though it seems that they might easily be made by a person conveniently situated and possessed of the necessary instruments. A careful examination by properly contrived thermometers of the relative temperatures of the air, the water, and the bed of the river and of the changes undergone by them during the above process, would probably go a great way towards solving the problem. I know no one better qualified for this undertaking than Mr. Knight, if he should at any future time have leisure and opportunity to direct towards it the same acuteness of observation and accuracy of investigation which have enabled him to make such important discoveries in the economy of the vegetable kingdom, and if the explanation of this phenomenon should ever lead to results of any importance to the cause of science, I shall feel sufficiently satisfied if it be deemed that I have been of any service in pointing out the way.
BLACKBURN,May 16th, 1818.
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CLITHEROE,October 20th, 1859.
To the Editor of the "Field."
"A Young Inquirer" asks what is the cause of that appearance so often met with in the autumn, resembling spider-webs. He says, if it be the production of that insect, how do you account for their hanging apparently unsuspended in the air, as it is seen fifty or sixty feet high, without a tree or any other object near to which it could be attached?
I suppose you have not time to give to such questions minutely, as your reply would lead one to infer that Gossamer proceeded from spiders in general; and if it be meant that all true spiders spin, it is no doubt correct; but the Gossamer which "A Young Inquirer" asks about is the production of a small black spider about the size of a flea, which was a true aeronaut long before Montgolfier or Lunardi, and if "A Young Inquirer" has access to either the "Linnean Transactions" or the first series of Loudon's "Magazine of Natural History," he will find particulars in the latter, showing that a violent controversy raged through the three first volumes between Mr. Blackwall and Dr. Murray on the question whether the ascent of this spider (A. AEronautica) was electric, or whether it merely travelled in the direction of the wind. But if "A Young Inquirer" would deserve his name, let him begin with these spiders and observe for himself; he will find the inquiry highly interesting.
He has no doubt frequently seen a small black spider creeping on his hat or clothes (if he lives in the country this must have occurred to him many times); this is the aeronautic spider. Let him take this upon his hand, and if he be in the house let him carry it to the open door or window, and allow it to creep up to the tip of his finger, which he must then hold in a horizontal position. When the spider finds it can proceed no further by creeping, it generally drops a few inches, where it remains suspended for a short time, apparently quite still, but if very closely observed another thread (Gossamer) may be seen proceeding from its vent, and when this has reached the length which the spider's instinct tells it is sufficient for the purpose, it cuts off the connection till then existing between it and the thread by which it has hitherto been suspended from the finger, and floats away into space. Very often it rises almost vertically, sometimes its course is nearly horizontal, and sometimes it is oblique.
I cannot say, as Mr. Murray does, that I have seen the spider goagainstthe wind, neither can I confirm Mr. Blackwall's assertions that he always goes right before the wind, for I have seen him go apparently across the current, so far as I could judge of the direction of the wind at the time.
If "A Young Inquirer" makes the experiment I have suggested, let him not be discouraged if the first he tries does not go off at all, as I have sometimes found this to be the case, which I accounted for by supposing that possibly the supply of materials might be exhausted at the time.
I do not remember that I ever saw one of these aeronautic spiders preying upon any insect, yet it must be for some such purpose that they ascend to great altitudes, sometimes in countless numbers, and the way they come down again is quite as curious as the manner in which they ascend.
Many years since, as I was walking over the hills in the neighbourhood of Blackburn, on a bright, still morning in September, thousands of small locks of what looked like cotton wool were slowly descending to the ground from various altitudes— some as high as I could see—and tens of thousands of similar locks were lying on the ground on both sides of the path by which I was travelling; and on examination I found that all these locks were Gossamer, some with the spider still with them, but generally deserted. The spiders when they wanted to come down, finding there was no descending current of air, or perhaps, as Mr. Murray says, no electricity, determined to descend inparachutes; they therefore had drawn up their cables hand over hand (as they may often be seen to do when they wish to ascend their own lines) until they accumulated a mass heavy enough to fall by its own weight, and carry them along with it.
I have seen Gossamer in this form at other times before and since, but in the likeness of a snow-shower I never saw it except on that occasion, and, if I recollect aright, the same enormous shower of Gossamer was observed to extend as far as Liverpool.
What induced these millions of spiders to go up at the same time, of course I do not know, and can only suppose that they went up to feed; but, as I have said previously, I never saw one of this species preying upon anything. The idea that they go aloft to kill theFuria Infernalisis too fanciful to deserve credit. Who knows whether theFuria Infernalisis anything else than a murderous Mrs. Harris—at all events, who has seen one, and what was it like?
I suppose they are true sportsmen, and disdaining to take their fish in nets, they, like thorough brothers of the angle, fish onlywith fine gut.
Gilbert White noticed one of these showers of Gossamer, and as his account is very interesting, I quote it. He says that on the 21st of September, 1741, intent upon field diversions, he rose before daybreak, but on going out he found the whole face of the country covered with a thick coat of cobweb drenched with dew, as if two or three setting-nets had been drawn one over the other. When his dogs attempted to hunt, their eyes were blinded and hoodwinked, so much that they were obliged to lie down and scrape themselves. This appearance was followed by a most lovely day. About 9 A.M. a shower of these webs (formed not of single threads, but of perfect flakes, some near an inch broad and five or six long) was observed falling from very elevated regions, which continued without interruption during the whole of the day, and they fell with a velocity which showed they were considerably heavier than the atmosphere. When the most elevated station in the country where this was observed was ascended, the webs were still to be seen descending from above, and twinkling like stars in the sun, so as to draw the attention of the most incurious. The flakes of the web on this occasion hung so thick upon the hedges and trees, that basketsful might have been collected. No one doubts (he observes) but that these webs are the production of small spiders.
These aerial spiders are of two sizes, although of the same colour and general appearance; they are probably male and female. At all events they do not vary in size more than other species of spiders when the sexes differ.
Has it been observed by naturalists that spiders eat their own webs? A large one that I used to feed when I was a lad with wasps, humble bees, and flesh-flies, used to do so occasionally. These insects were so strong that they often ruined the web in their efforts to escape, and the spider, quite aware of the rough customers it had to deal with, would often coil a cable of many folds round them before venturing to seize them with its mandibles. It would, if the web was ruined by the struggles of the insect, deliberately gorge it, which I accounted for by supposing that unless it did so it would not be able to secrete a sufficient supply of material to enable it to spin another.
The leaping spiders are another curious species, which construct no webs, although they spin threads. This spider may be seen frequently on the walls of houses, and if carefully watched it will be seen to range up and down in quest of small gnats and other insects; when it observes one it creeps to within about two inches of it, and backing slightly, it appears to hesitate for a moment, and then springs upon the fly, but always before doing so it fixes a thread to the spot from whence it springs, so that if the fly happens to be too strong for it, and is able to detach itself from the wall, they both remain suspended from the thread which has been previously fixed by the spider. This I have seen more than once.
They sometimes venture on larger game than the small gnats. One I was watching one day came upon one of the largeEphemera(the Browndrake), an insect ten times as large as the spider, but after many points (for the setting of the spider before it springs is very similar in manner to that of a thoroughbred pointer [17]), in which it kept varying its position, apparently to gain some advantage, it gave up the attempt, discretion proving the better part of valour.
When botanizing on Erris Begh (in Connemara), this summer, I passed through many spider-lines so strong as to offer a very sensible resistance before breaking. I don't remember to have ever before met with them so strong and tenacious, and the makers of optical instruments might there have found abundance of threads which I am told are valuable ascross-wiresfor transit- instruments and theodolites. I did not meet with any of the spiders that had thrown out these lines, but judging of them by their works I suppose they must have been large ones.
One of your correspondents was inquiring a few weeks since how it was that a spider could throw out a long line between two trees or buildings at a considerable distance from each other. This seems to me to be very easily explained, if we reason from the analogy of the flying spider. The spider seems to throw out a line, trusting it will catch somewhere or other, and it is able to ascertain it has done so by pulling at it, and when it finds that it is firmly fixed it starts off to travel upon it, as I have occasionally noticed.
Everyone has noticed how carefully the spider carries her cocoon of eggs attached to the vent, and how disconsolate she appears to be when deprived of them; but I don't think it is so generally known that some of the spiders carry their young on their backs for some time after they are hatched. I remember seeing an instance of this one day when on the Moors, grouse-shooting. I saw what seemed to be a very curious insect travelling on the ling (heather), and on stooping down to examine it I found it was a large spider, upon the back of which (in fact, all over it) were clustered some dozens of young ones, about the size of pins' heads; she also seemed to guard them with great care, and seemed much afraid of losing them.
[1] There is a fish somewhat resembling the Brambling in the Dunsop, a tributary of the Hodder, where it is known by the name of the Bull Penk.
[2] My opinion that neither Trout nor Salmon spawn every year is I think strongly corroborated by the fact, that previous to the Act of 1861 the London fish market was supplied with Salmon of the largest size, and of the best quality, in October, November, and December. When these fish were examined, it was found that the ovaries were but small, and the individual ova were not larger than mustard seed. These fish could not have spawned that season, nor would they have done so if left alive, if the growth of the ova in the ovaries is uniform—I mean if the growth of the ova is as great in one month as another—because in May and June the ova in a female Salmon is four times as large as these were in November.
Again, when the gas tank at Settle was emptied into the Ribble, in September, 1861, all the fish so far as was known were killed between that place and Mitton, Salmon as well as Par and Trout. Supposing that Salmon spawn every year, and that the Smolts come up the river, as Grilse in the summer of the same year in which they have gone to the sea in the spring, there ought to have been a great scarcity of both Grilse and Salmon in the Ribble in the year 1862, but so far was this from being the case, that both Grilse and Salmon were more abundant that season than they had been for some years previously, but there was a scarcity of both in 1863.
Again, when the Smolts were turned out of the breeding ponds at Dohulla, Galway, the experiment was looked upon as a failure because no Grilse returned the same season, not one having showed itself, but many came the summer after, proving pretty conclusively that in some rivers, at all events, the Smolt requires a year's residence in the sea before it returns as Grilse.
[3] In the evidence of Mr. George Hogarth, it is stated that he saw upwards of ninety Kelt fish in the mill lead at Grandholme, on the Don, May 6th.
[4] Salmon are said to produce 18,000 or 20,000 eggs each, and I have no doubt that a large Salmon will produce more, as one I examined a year or two ago, of about ten pounds weight, had a roe which weighed two pounds nine ounces, and the skin in which the eggs were enveloped (they were not in the loose state in which they are found just before exclusion) weighed three ounces, after all the eggs were washed from it; so that there were thirty-eight ounces of eggs. I weighed fifty of them, and found they weighed sixty-five grains. At that rate, thirty-eight ounces would give 12,788, and 300 lbs. 1,615,000; but as they would be much lighter when dried and potted than when taken from the belly of the fish, we may safely estimate that the 300 lbs. would contain 2,000,000, a prodigious number to pass through the hands of one tackle maker in a season.
[5] From "Loudon's Magazine of Natural History."
[6] I have frequently found, when catching Trout for this purpose, that the milt and roe were not ready for exclusion; when this was the case, I put them into a wire cage, which I sunk in the water, examining the fish every week, until I found they were in a fit state for the experiment.
[7] I fancy that if the ova come in contact with the air on exclusion, they are not so readily impregnated as if they are always covered with the water, and therefore I have laid some stress on the desirableness of keeping the air excluded from the ova as much as possible.
[8] There is, however, one fact which must lead a casual observer to suppose that the ova are impregnated twelve months before exclusion. It is this: the male Par (Salmon fry) are at this season, October, full of milt, almost ready for exclusion; whilst, in the female, the ova are so small that they require a microscope to see them individually, and the whole ovary is merely like a thread, leading to the conclusion that either the milt of the male is not required for the female Par, or the ova are impregnated twelve months before exclusion. The fact is, that the milt of the Par is used to impregnate the ova of the Salmon on the spawning beds.
[9] When I commenced this paper I had no doubt that hybrids had been produced between the Sprod (sea Trout) and the common Trout; since then, having seen the fry said to be so produced, and on making some further inquiries, I find there is some doubt whether the female was aSprod, or merely a white Trout, and therefore I cannot confidently assert (as some time ago I believed I could) that hybrid fish had already been produced. As some of my readers may not know what aSprodis, it may be necessary to explain. In the Ribble we have a fish ascending from the sea in July and August, weighing from six to ten ounces, which, in appearance at least, is a miniature Salmon. I believe the same fish is called a Whitling in Scotland. Besides this, we have a similar but larger fish, which begins to come a little earlier, and which weighs from one to three pounds; this, in the Ribble, is called a Mort (in Scotland a sea Trout). Both these fish (if they are two species) afford splendid sport to the angler, who must never consider them beaten until he has them in the landing-net. They are also delicate eating.
Note on cross-breeding of Fish.
Since the above paper was published, the breeding of Hybrids has been successfully accomplished. I have had fish sent from two different gentlemen living on the banks of the reservoirs belonging to the Liverpool Waterworks; these were beautiful fish (three in number), more like the sea Trout than the Salmon, and the largest of them weighing two pounds. I had put them into the brooks running into the reservoirs three years before.
I also learn from a friend that a beautiful specimen of theombreChevalier(French Char) was taken out of the Rivington reservoir.About a thousand had been put there by me two years before.
[10] Persons conversant with the habits of birds will readily comprehend me; for the sake of those who do not, I will just observe that the flight of all the Wagtails is very peculiar, being a succession of great leaps in the air (if I may be allowed the expression), which form a series of curves, the bird rising considerably at the commencement of each effort, and sinking again at the close.
[11] The intrepid and unfortunate traveller Joseph Ritchie, who accompanied Captain Lyon's expedition to Fezzan, and died there in 1819. Mr. Ritchie was a native of Otley, and an intimate friend of Mr. Garnett and his brothers. The beautiful poem from which the quotation is taken is printed in Alaric Watts's "Poetical Album."
[12] 1853.—I regret that in 1853, and for some years previous, we have not seen one. I fear they are extinct. The smaller kind are still numerous.
[13] The male Par is an exception to this rule.
[14] It appears to be a beautiful provision of Nature that mixture with water should increase the sphere of its action. Spallanzani found by actual experiment that three grains of the seed of a male frog might be diluted with a pint of water without destroying its stimulating power. See "Dissertations," vol. ii. p. 142, chap. 3, Ed. "Mag. Nat. History."
[15] Mr. Thomson, of Primrose.
[16] Assistant Keeper of Printed Books in the British Museum. Author of "Philological Essays," &c.
[17] The toad, when going to take a bee, points for a second or two as beautifully as the best-trained pointer before it strikes with its tongue.