I am a very good sod layer, and used to lay very large lawns--half to three-quarters of an acre. I cut the sods as follows: Take a board eight to nine inches wide, four, five, or six feet long, and cut downward all around the board, then turn the board over and cut again alongside the edge of the board, and so on as many sods as needed. Then cut the turf with a sharp spade, all the same lengths. Begin on one end, and roll together. Eight inches by five feet is about as much as a man can handle conveniently. It is very easy to load them on a wagon, cart, or barrow, and they can be quickly laid. After laying a good piece, sprinkle a little with a watering pot, if the sods are dry; then use the back of the spade to smooth them a little. If a very fine effect is wanted, throw a shovelful or two of good earth over each square yard, and smooth it with the back of a steel rake.
F.H.
[COUNTRY GENTLEMAN.]
The Western New York Society met at Rochester, January 26.
New Apples, Pears, Grapes, etc.--Wm. C Barry, secretary of the committee on native fruits, read a full report. Among the older varieties of the apple, he strongly recommended Button Beauty, which had proved so excellent in Massachusetts, and which had been equally successful at the Mount Hope Nurseries at Rochester; the fine growth of the tree and its great productiveness being strongly in its favor. The Wagener and Northern Spy are among the finer sorts. The Melon is one of the best among the older sorts; the fruit being quite tender will not bear long shipment, but it possesses great value for home use, and being a poor grower, it had been thrown aside by nurserymen and orchardists. It should be top-grafted on more vigorous sorts. The Jonathan is another fine sort of slender growth, which should be top-grafted.
Among new pears, Hoosic and Frederic Clapp were highly commended for their excellence. Some of the older peaches of fine quality had of late been neglected, and among them Druid Hill and Brevoort.
Among the many new peaches highly recommended for their early ripening, there was great resemblance to each other, and some had proved earlier than Alexander.
Of the new grapes, Lady Washington was the most promising. The Secretary was a failure. The Jefferson was a fine sort, of high promise.
Among the new white grapes, Niagara, Prentiss, and Duchess stood pre-eminent, and were worthy of the attention of cultivators. The Vergennes, from Vermont, a light amber colored sort, was also highly commended. The Elvira, so highly valued in Missouri, does not succeed well here. Several facts were stated in relation to the Delaware grape, showing its reliability and excellence.
Several new varieties of the raspberry were named, but few of them were found equal to the best old sorts. If Brinckle's Orange were taken as a standard for quality, it would show that none had proved its equal in fine quality. The Caroline was like it in color, but inferior in flavor. The New Rochelle was of second quality. Turner was a good berry, but too soft for distant carriage.
Of the many new strawberries named, each seemed to have some special drawback. The Bidwell, however, was a new sort of particular excellence, and Charles Downing thinks it the most promising of the new berries.
Discussion on Grapes.--C. W. Beadle, of Ontario, in allusion to Moore's Early grape, finds it much earlier than the Concord, and equal to it in quality, ripening even before the Hartford. S. D. Willard, of Geneva, thought it inferior to the Concord, and not nearly so good as the Worden. The last named was both earlier and better than the Concord, and sold for seven cents per pound when the Concord brought only four cents. C. A. Green, of Monroe County, said the Lady Washington proved to be a very fine grape, slightly later than Concord. P. L. Perry, of Canandaigua, said that the Vergennes ripens with Hartford, and possesses remarkable keeping qualities, and is of excellent quality and free from pulp. He presented specimens which had been kept in good condition. He added, in relation to the Worden grape, that some years ago it brought 18 cents per pound in New York when the Concord sold three days later for only 8 cents. [In such comparisons, however, it should be borne in mind that new varieties usually receive more attention and better culture, giving them an additional advantage.]
The Niagara grape received special attention from members. A. C. Younglove, of Yates County, thought it superior to any other white grape for its many good qualities. It was a vigorous and healthy grower, and the clusters were full and handsome. W. J. Fowler, of Monroe County, saw the vine in October, with the leaves still hanging well, a great bearer and the grape of fine quality. C. L. Hoag, of Lockport, said he began to pick the Niagara on the 26th of August, but its quality improved by hanging on the vine. J. Harris, of Niagara County, was well acquainted with the Niagara, and indorsed all the commendation which had been uttered in its favor. T. C. Maxwell said there was one fault--we could not get it, as it was not in market. W. C. Barry, of Rochester, spoke highly of the Niagara, and its slight foxiness would be no objection to those who like that peculiarity. C. L. Hoag thought this was the same quality that Col. Wilder described as "a little aromatic." A. C. Younglove found the Niagara to ripen with the Delaware. Inquiry being made relative to the Pockington grape, H. E. Hooker said it ripened as early as the Concord. C. A. Green was surprised that it had not attracted more attention, as he regarded it as a very promising grape. J. Charlton, of Rochester, said that the fruit had been cut for market on the 29th of August, and on the 6th of September it was fully ripe; but he has known it to hang as late as November. J. S. Stone had found that when it hung as late as November it became sweet and very rich in flavor.
New Peaches.--A. C. Younglove had found such very early sorts as Alexander and Amsden excellent for home use, but not profitable for market. The insects and birds made heavy depredations on them. While nearly all very early and high-colored sorts suffer largely from the birds, the Rivers, a white peach, does not attract them, and hence it may be profitable for market if skillfully packed; rough and careless handling will spoil the fruit. He added that the Wheatland peach sustains its high reputation, and he thought it the best of all sorts for market, ripening with Late Crawford. It is a great bearer, but carries a crop of remarkably uniform size, so that it is not often necessary to throw out a bad specimen. This is the result of experience with it by Mr. Rogers at Wheatland, in Monroe County, and at his own residence in Vine Valley. S. D. Willard confirmed all that Mr. Younglove had said of the excellence of the Rivers peach. He had ripened the Amsden for several years, and found it about two weeks earlier than the Rivers, and he thought if the Amsden were properly thinned, it would prevent the common trouble of its rotting; such had been his experience. E. A. Bronson, of Geneva, objected to making very early peaches prominent for marketing, as purchasers would prefer waiting a few days to paying high prices for the earliest, and he would caution people against planting the Amsden too largely, and its free recommendation might mislead. May's Choice was named by H. E. Hooker as a beautiful yellow peach, having no superior in quality, but perhaps it may not be found to have more general value than Early and Late Crawford. It is scarcely distinguishable in appearance from fine specimens of Early Crawford. W. C. Barry was called on for the most recent experience with the Waterloo, but said he was not at home when it ripened, but he learned that it had sustained its reputation. A. C. Younglove said that the Salway is the best late peach, ripening eight or ten days after the Smock. S. D. Willard mentioned an orchard near Geneva, consisting of 25 Salway trees, which for four years had ripened their crop and had sold for $4 per bushel in the Philadelphia market, or for $3 at Geneva--a higher price than for any other sort--and the owner intends to plant 200 more trees. W. C. Barry said the Salway will not ripen at Rochester. Hill's Chili was named by some members as a good peach for canning and drying, some stating that it ripens before and others after Late Crawford. It requires thinning on the tree, or the fruit will be poor. The Allen was pronounced by Mr. Younglove as an excellent, intensely high-colored late peach.
Insects Affecting Horticulture.--Mr. Zimmerman spoke of the importance of all cultivators knowing so much of insects and their habits as to distinguish their friends from their enemies. When unchecked they increase in an immense ratio, and he mentioned as an instance that the green fly (Aphis) in five generations may become the parent of six thousand million descendants. It is necessary, then, to know what other insects are employed in holding them in check, by feeding on them. Some of our most formidable insects have been accidentally imported from Europe, such as the codling moth, asparagus beetle, cabbage butterfly, currant worm and borer, elm-tree beetle, hessian fly, etc.; but in nearly every instance these have come over without bringing their insect enemies with them, and in consequence they have spread more extensively here than in Europe. It was therefore urged that the Agricultural Department at Washington be requested to import, as far as practicable, such parasites as are positively known to prey on noxious insects. The cabbage fly eluded our keen custom-house officials in 1866, and has enjoyed free citizenship ever since. By accident, one of its insect enemies (a small black fly) was brought over with it, and is now doing excellent work by keeping the cabbage fly in check.
The codling moth, one of the most formidable fruit destroyers, may be reduced in number by the well-known paper bands; but a more efficient remedy is to shower them early in the season with Paris green, mixed in water at the rate of only one pound to one hundred gallons of water, with a forcing pump, soon after blossoming. After all the experiments made and repellents used for the plum curculio, the jarring method is found the most efficient and reliable, if properly performed. Various remedies for insects sometimes have the credit of doing the work, if used in those seasons when the insects happen to be few. With some insects, the use of oil is advantageous, as it always closes up their breathing holes and suffocates them. The oil should be mixed with milk, and then diluted as required, as the oil alone cannot be mixed with the water. As a general remedy, Paris green is the strongest that can be applied. A teaspoonful to a tablespoonful, in a barrel of water, is enough. Hot water is the best remedy for house plants. Place one hand over the soil, invert the pot, and plunge the foliage for a second only at a time in water heated to from 150° to 200°F, according to the plants; or apply with a fine rose. The yeast remedy has not proved successful in all cases.
Among beneficial insects, there are about one hundred species of lady bugs, and, so far as known, all are beneficial. Cultivators should know them. They destroy vast quantities of plant lice. The ground beetles are mostly cannibals, and should not be destroyed. The large black beetle, with coppery dots, makes short work with the Colorado potato beetles; and a bright green beetle will climb trees to get a meal of canker worms. Ichneumon flies are among our most useful insects. The much-abused dragon flies are perfectly harmless to us, but destroy many mosquitoes and flies.
Among insects that attack large fruits is the codling moth, to be destroyed by paper bands, or with Paris green showered in water. The round-headed apple-tree borer is to be cut out, and the eggs excluded with a sheet of tarred paper around the stem, and slightly sunk in the earth. For the oyster-shell bark louse, apply linseed oil. Paris green, in water, will kill the canker worm. Tobacco water does the work for plant lice. Peach-tree borers are excluded with tarred or felt paper, and cut out with a knife. Jar the grape flea beetle on an inverted umbrella early in the morning. Among small-fruit insects, the strawberry worms are readily destroyed with hellebore, an ounce to a gallon of warm water. The same remedy destroys the imported currant worm.
Insect Destroyers.--Prof. W. Saunders, of the Province of Ontario, followed Mr. Zimmerman with a paper on other departments of the same general subject, which contained much information and many suggestions of great value to cultivators. He had found Paris green an efficient remedy for the bud-moth on pear and other trees. He also recommends Paris green for the grapevine flea beetle. Hellebore is much better for the pear slug than dusting with sand, as these slugs, as soon as their skin is spoiled by being sanded, cast it off and go on with their work of destruction as freely as ever, and this they repeat. He remarked that it is a common error that all insects are pests to the cultivator. There are many parasites, or useful ones, which prey on our insect enemies. Out of 7,000 described insects in this country, only about 50 have proved destructive to our crops. Parasites are much more numerous. Among lepidopterous insects (butterflies, etc.), there are very few noxious species; many active friends are found among the Hymenoptera (wasps, etc.), the ichneumon flies pre-eminently so; and in the order Hemiptera (bugs proper) are several that destroy our enemies. Hence the very common error that birds which destroy insects are beneficial to us, as they are more likely to destroy our insect friends than the fewer enemies. Those known asflycatchersmay do neither harm nor good; so far as they eat the wheat-midge and Hessian fly they confer a positive benefit; in other instances they destroy both friends and enemies. Birds that are only partly insectivorous, and which eat grain and fruit, may need further inquiry. Prof. S. had examined the stomachs of many such birds, and particularly of the American robin, and the only curculio he ever found in any of these was a single one in a whole cherry which the bird had bolted entire. Robins had proved very destructive to his grapes, but had not assisted at all in protecting his cabbages growing alongside his fruit garden. These vegetables were nearly destroyed by the larvae of the cabbage fly, which would have afforded the birds many fine, rich meals. This comparatively feeble insect has been allowed by the throngs of birds to spread over the whole continent. A naturalist in one of the Western States had examined several species of the thrush, and found they had eaten mostly that class of insects known as our friends.
Prof. S. spoke of the remedies for root lice, among which were hot water and bisulphide of carbon. Hot water will get cold before it can reach the smaller roots, however efficient it may be showered on leaves. Bisulphide of carbon is very volatile, inflammable, and sometimes explosive, and must be handled with great care. It permeates the soil, and if in sufficient quantity may be effective in destroying the phylloxera; but its cost and dangerous character prevent it from being generally recommended.
Paris green is most generally useful for destroying insects. As sold to purchasers, it is of various grades of purity. The highest in price is commonly the purest, and really the cheapest. A difficulty with this variable quality is that it cannot be properly diluted with water, and those who buy and use a poor article and try its efficacy, will burn or kill their plants when they happen to use a stronger, purer, and more efficient one. Or, if the reverse is done, they may pronounce it a humbug from the resulting failure. One teaspoonful, if pure, is enough for a large pail of water; or if mixed with flour, there should be forty or fifty times as much. Water is best, as the operator will not inhale the dust. London purple is another form of the arsenic, and has very variable qualities of the poison, being merely refuse matter from manufactories. It is more soluble than Paris green, and hence more likely to scorch plants. On the whole, Paris green is much the best and most reliable for common use.
At the close of Prof. Saunders' remarks some objections were made by members present to the use of Paris green on fruit soon after blossoming, and Prof. S. sustained the objection, in that the knowledge that the fruit had been showered with it would deter purchasers from receiving it, even if no poison could remain on it from spring to autumn. A man had brought to him potatoes to analyze for arsenic, on which Paris green had been used, and although it was shown to him that the poison did not reach the roots beneath the soil, and if it did it was insoluble and could not enter them, he was not satisfied until a careful analysis was made and no arsenic at all found in them. A member said that in mixing with plaster there should be 100 or 150 pounds of plaster to one of the Paris green, and that a smaller quantity, by weight, of flour would answer, as that is a more bulky article for the same weight.
During the most of the present year, the writers have been engaged in the study of the fishes of the Pacific coast of the United States, in the interest of the U.S. Fish Commission and the U.S. Census Bureau. The following pages contain the principal facts ascertained concerning the salmon of the Pacific coast. It is condensed from our report to the U.S. Census Bureau, by permission of Professor Goode, assistant in charge of fishery investigations.
There are five species of salmon (Oncorhynchus) in the waters of the North Pacific. We have at present no evidence of the existence of any more on either the American or the Asiatic side.
These species may be called the quinnat or king salmon, the blue-back salmon or red-fish, the silver salmon, the dog salmon, and the hump-back salmon, orOncorhynchus chouicha, nerka, kisutch, keta, andgorbuscha. All these species are now known to occur in the waters of Kamtschatka as well as in those of Alaska and Oregon.
As vernacular names of definite application, the following are on record:
a. Quinnat--Chouicha, king salmon, e'quinna, saw-kwey, Chinnook salmon, Columbia River salmon, Sacramento salmon, tyee salmon, Monterey salmon, deep-water salmon, spring salmon, ek-ul-ba ("ekewan") (fall run).
b. Blue-bock--krasnaya ryba, Alaska red-fish, Idaho red fish, sukkegh, Frazer's River salmon, rascal, oo-chooy-ha.
c. Silver salmon--kisutch, winter salmon, hoopid, skowitz, coho, bielaya ryba, o-o-wun.
d. Dog salmon--kayko, lekai, ktlawhy, qualoch, fall salmon, o-le-a-rah. The males ofallthe species in the fall are usually known as dog salmon, or fall salmon.
e. Hump-back--gorbuscha, haddo, hone, holia, lost salmon, Puget Sound salmon, dog salmon (of Alaska).
Of these species, the blue-back predominates in Frazer's River, the silver salmon in Puget Sound, the quinnat in the Columbia and the Sacramento, and the silver salmon in most of the small streams along the coast. All the species have been seen by us in the Columbia and in Frazer's River; all but the blue-back in the Sacramento, and all but the blue-back in waters tributary to Puget Sound. Only the quinnat has been noticed south of San Francisco, and its range has been traced as far as Ventura River, which is the southernmost stream in California which is not muddy and alkaline at its mouth.
Of these species, the quinnat and blue-back salmon habitually "run" in the spring, the others in the fall. The usual order of running in the rivers is as follows:nerka, chouicha, kisutch, gorbuscha, keta.
The economic value of the spring running salmon is far greater than that of the other species, because they can be captured in numbers when at their best, while the others are usually taken only after deterioration.
The habits of the salmon in the ocean are not easily studied. Quinnat and silver salmon of every size are taken with the seine at almost any season in Puget Sound. The quinnat takes the hook freely in Monterey bay, both near the shore and at a distance of six or eight miles out. We have reason to believe that these two species do not necessarily seek great depths, but probably remain not very far from the mouth of the rivers in which they were spawned.
The blue-back and the dog salmon probably seek deeper water, as the former is seldom or never taken with the seine in the ocean, and the latter is known to enter the Straits of Fuca at the spawning season.
The great majority of the quinnat salmon and nearly all blue-back salmon enter the rivers in the spring. The run of both begins generally the last of March; it lasts, with various modifications and interruptions, until the actual spawning season in November; the time of running and the proportionate amount of each of the subordinate runs, varying with each different river. In general, the runs are slack in the summer and increase with the first high water of autumn. By the last of August only straggling blue-backs can be found in the lower course of any stream, but both in the Columbia and the Sacramento the quinnat runs in considerable numbers till October at least. In the Sacramento the run is greatest in the fall, and more run in the summer than in spring. In the Sacramento and the smaller rivers southward, there is a winter run, beginning in December.
The spring salmon ascend only those rivers which are fed by the melting snows from the mountains, and which have sufficient volume to send their waters well out to sea. Such rivers are the Sacramento, Rogue, Klamath, Columbia, and Frazer's rivers.
Those salmon which run in the spring are chiefly adults (supposed to be at least three years old). Their milt and spawn are no more developed than at the same time in others of the same species which will not enter the rivers until fall. It would appear that the contact with cold fresh water, when in the ocean, in some way caused them to turn toward it and to "run," before there is any special influence to that end exerted by the development of the organs of generation.
High water on any of these rivers in the spring is always followed by an increased run of salmon. The canners think, and this is probably true, that salmon which would not have run till later are brought up by the contact with the cold water. The cause of this effect of cold fresh water is not understood. We may call it an instinct of the salmon, which is another way of expressing our ignorance. In general, it seems to be true that in those rivers and during those years when the spring run is greatest, the fall run is least to be depended on.
As the season advances, smaller and younger salmon of these two species (quinnat and blue-back) enter the rivers to spawn, and in the fall these young specimens are very numerous. We have thus far failed to notice any gradations in size or appearance of these young fish by which their ages could be ascertained. It is, however, probable that some of both sexes reproduce at the age of one year. In Frazer's River, in the fall, quinnat male grilse of every size, from eight inches upward, were running, the milt fully developed, but usually not showing the hooked jaws and dark colors of the older males. Females less than eighteen inches in length were rare. All, large and small, then in the river, of either sex, had the ovaries or milt well developed.
Little blue-backs of every size down to six inches are also found in the Upper Columbia in the fall, with their organs of generation fully developed. Nineteen twentieths of these young fish are males, and some of them have the hooked jaws and red color of the old males.
The average weight of the quinnat in the Columbia in the spring is twenty-two pounds; in the Sacramento about sixteen. Individuals weighing from forty to sixty pounds are frequently found in both rivers, and some as high as eighty pounds are reported. It is questioned whether these large fishes are:
(a.) Those which, of the same age, have grown more rapidly;
(b.) Those which are older but have, for some reason, failed to spawn; or,
(c.) Those which have survived one or more spawning seasons.
All of these origins may be possible in individual cases; we are, however, of the opinion that the majority of these large fish are those which have hitherto run in the fall and so may have survived the spawning season previous.
Those fish which enter the rivers in the spring continue their ascent until death or the spawning season overtakes them. Probably none of them ever return to the ocean, and a large proportion fail to spawn. They are known to ascend the Sacramento as far as the base of Mount Shasta, or to its extreme head-waters, about four hundred miles. In the Columbia they are known to ascend as far as the Bitter Root Mountains, and as far as the Spokan Falls, and their extreme limit is not known. This is a distance of six to eight hundred miles.
At these great distances, when the fish have reached the spawning grounds, besides the usual changes of the breeding season, their bodies are covered with bruises on which patches of white fungus develop. The fins become mutilated, their eyes are often injured or destroyed; parasitic worms gather in their gills, they become extremely emaciated, their flesh becomes white from the loss of the oil, and as soon as the spawning act is accomplished, and sometimes before, all of them die. The ascent of the Cascades and the Dalles probably causes the injury or death of a great many salmon.
When the salmon enter the river they refuse bait, and their stomachs are always found empty and contracted. In the rivers they do not feed, and when they reach the spawning grounds their stomachs, pyloric coeca and all, are said to be no larger than one's finger. They will sometimes take the fly, or a hook baited with salmon roe, in the clear waters of the upper tributaries, but there is no other evidence known to us that they feed when there. Only the quinnat and blue-back (then called red-fish) have been found in the fall at any great distance from the sea.
The spawning season is probably about the same for all the species. It varies for all in different rivers and in different parts of the same river, and doubtless extends from July to December.
The manner of spawning is probably similar for all the species, but we have no data for any except the quinnat. In this species the fish pair off, the male, with tail and snout, excavates a broad shallow "nest" in the gravelly bed of the stream, in rapid water, at a depth of one to four feet; the female deposits her eggs in it, and after the exclusion of the milt, they cover them with stones and gravel. They then float down the stream tail foremost. A great majority of them die. In the head-waters of the large streams all die, unquestionably. In the small streams, and near the sea, an unknown percentage probably survive. The young hatch in about sixty days, and most of them return to the ocean during the high water of the spring.
The salmon of all kinds in the spring are silvery, spotted or not according to the species, and with the mouth about equally symmetrical in both sexes.
As the spawning season approaches the female loses her silvery color, becomes more slimy, the scales on the back partly sink into the skin, and the flesh changes from salmon red and becomes variously paler, from the loss of the oil, the degree of paleness varying much with individuals and with inhabitants of different rivers.
In the lower Sacramento the flesh of the quinnat in either spring or fall is rarely pale. In the Columbia, a few with pale flesh are sometimes taken in spring, and a good many in the fall. In Frazer's River the fall run of the quinnat is nearly worthless for canning purposes, because so many are white meated. In the spring very few are white meated, but the number increases towards fall, when there is every variation, some having red streaks running through them, others being red toward the head and pale toward the tail. The red and pale ones cannot be distinguished externally, and the color is dependent neither on age nor sex. There is said to be no difference in the taste, but there is no market for canned salmon not of the conventional orange color.
As the season advances, the differences between the males and the females become more and more marked, and keep pace with the development of the milt, as is shown by dissection.
The males have: (a.) The premaxillaries and the tip of the lower jaw more and more prolonged; both of them becoming finally strongly and often extravagantly hooked, so that either they shut by the side of each other like shears, or else the mouth cannot be closed. (b.) The front teeth become very long and canine-like, their growth proceeding very rapidly, until they are often half an inch long. (c.) The teeth on the vomer and tongue often disappear. (d.) The body grows more compressed and deeper at the shoulders, so that a very distinct hump is formed; this is more developed in0. gorbuscha, but is found in all. (e.) The scales disappear, especially on the back, by the growth of spongy skin. (f.) The color changes from silvery to various shades of black and red or blotchy, according to the species. The blue-back turns rosy red, the dog salmon a dull, blotchy red, and the quiunat generally blackish.
These distorted males are commonly considered worthless, rejected by the canners and salmon-salters, but preserved by the Indians. These changes are due solely to influences connected with the growth of the testes. They are not in any way due to the action of fresh water. They take place at about the same time in the adult males of all species, whether in the ocean or in the rivers. At the time of the spring runs all are symmetrical. In the fall, all males of whatever species are more or less distorted. Among the dog salmon, which run only in the fall, the males are hooked-jawed and red-blotched when they first enter the Straits of Fuca from the outside. The hump-back, taken in salt water about Seattle, shows the same peculiarities. The male is slab-sided, hook-billed, and distorted, and is rejected by the canners. No hook-jawedfemalesof any species have been seen.
It is not positively known that any hook-jawed male survives the reproductive act. If any do, their jaws must resume the normal form.
On first entering a stream the salmon swim about as if playing: they always head toward the current, and this "playing" may be simply due to facing the flood tide. Afterwards they enter the deepest parts of the stream and swim straight up, with few interruptions. Their rate of travel on the Sacramento is estimated by Stone at about two miles per day; on the Columbia at about three miles per day.
As already stated, the economic value of any species depends in great part on its being a "spring salmon." It is not generally possible to capture salmon of any species in large numbers until they have entered the rivers, and the spring salmon enter the rivers long before the growth of the organs of reproduction has reduced the richness of the flesh. The fall salmon cannot be taken in quantity until their flesh has deteriorated: hence the "dog salmon" is practically almost worthless, except to the Indians, and the hump-back salmon is little better. The silver salmon, with the same breeding habits as the dog salmon, is more valuable, as it is found in Puget Sound for a considerable time before the fall rains cause the fall runs, and it may be taken in large numbers with seines before the season for entering the rivers. The quinnat salmon, from its great size and abundance, is more valuable than all other fishes on our Pacific coast together. The blue back, similar in flesh but much smaller and less abundant, is worth much more than the combined value of the three remaining species.
The fall salmon of all species, but especially the dog salmon, ascend streams but a short distance before spawning. They seem to be in great anxiety to find fresh water, and many of them work their way up little brooks only a few inches deep, where they soon perish miserably, floundering about on the stones. Every stream, of whatever kind, has more or less of these fall salmon.
It is the prevailing impression that the salmon have some special instinct which leads them to return to spawn in the same spawning grounds where they were originally hatched. We fail to find any evidence of this in the case of the Pacific coast salmon, and we do not believe it to be true. It seems more probable that the young salmon, hatched in any river, mostly remain in the ocean within a radius of twenty, thirty, or forty miles of its mouth. These, in their movements about in the ocean, may come into contact with the cold waters of their parent rivers, or perhaps of any other river, at a considerable distance from the shore. In the case of the quinnat and the blue-back, their "instinct" leads them to ascend these fresh waters, and in a majority of cases these waters will be those in which the fishes in question were originally spawned. Later in the season the growth of the reproductive organs leads them to approach the shore and to search for fresh waters, and still the chances are that they may find the original stream. But undoubtedly many fall salmon ascend, or try to ascend, streams in which no salmon was ever hatched.
It is said of the Russian River and other California rivers, that their mouths in the time of low water in summer generally become entirely closed by sand bars, and that the salmon, in their eagerness to ascend them, frequently fling themselves entirely out of water on the beach. But this does not prove that the salmon are guided by a marvelous geographical instinct which leads them to their parent river. The waters of Russian River soak through these sand bars, and the salmon "instinct," we think, leads them merely to search for fresh waters.
This matter is much in need of further investigation; at present, however, we find no reason to believe that the salmon enter the Rogue River simply because they were spawned there, or that a salmon hatched in the Clackamas River is any the more likely on that account to return to the Clackamas than to go up the Cowlitz or the Deschutes.
"At the hatchery on Rogue River, the fish are stripped, marked and set free, and every year since the hatchery has been in operation some of the marked fish have been re-caught. The young fry are also marked, but none of them have been recaught."
This year the run of silver salmon in Frazer's River was very light, while on Puget Sound the run was said by the Indians to be greater than ever known before. Both these cases may be due to the same cause, the dry summer, low water, and consequent failure of the salmon to find the rivers. The run in the Sound is much more irregular than in the large rivers. One year they will abound in one bay and its tributary stream and hardly be seen in another, while the next year the condition will be reversed. At Cape Flattery the run of silver salmon for the present year was very small, which fact was generally attributed by the Indians to the birth of twins at Neah Bay.
In regard to the diminution of the number of salmon on the coast. In Puget's Sound, Frazer's River, and the smaller streams, there appears to be little or no evidence of this. In the Columbia River the evidence appears somewhat conflicting; the catch during the present year (1880) has been considerably greater than ever before (nearly 540,000 cases of 48 lb. each having been packed), although the fishing for three or four years has been very extensive. On the other hand, the high water of the present spring has undoubtedly caused many fish to become spring salmon which would otherwise have run in the fall. Moreover, it is urged that a few years ago, when the number caught was about half as great as now, the amount of netting used was perhaps one-eighth as much. With a comparatively small outfit the canners caught half the fish, now with nets much larger and more numerous, they catch them all, scarcely any escaping during the fishing season (April 1 to August 1). Whether an actual reduction in the number of fish running can be proven or not, there can be no question that the present rate of destruction of the salmon will deplete the river before many years. A considerable number of quinnat salmon run in August and September, and some stragglers even later; these now are all which keep up the supply of fish in the river. The non-molestation of this fall run, therefore, does something to atone for the almost total destruction of the spring run.
This, however, is insufficient. A well-ordered salmon hatchery is the only means by which the destruction of the salmon in the river can be prevented. This hatchery should be under the control of Oregon and Washington, and should be supported by a tax levied on the canned fish. It should be placed on a stream where the quinnat salmon actually come to spawn.
It has been questioned whether the present hatchery on the Clackamas River actually receives the quinnat salmon in any numbers. It is asserted, in fact, that the eggs of the silver salmon and dog salmon, with scattering quinnat, are hatched there. We have no exact information as to the truth of these reports, but the matter should be taken into serious consideration.
On the Sacramento there is no doubt of the reduction of the number of salmon; this is doubtless mainly attributable to over-fishing, but in part it may be due to the destruction of spawning beds by mining operations and other causes.
As to the superiority of the Columbia River salmon, there is no doubt that the quinnat salmon average larger and fatter in the Columbia than in the Sacramento and in Puget Sound. The difference in the canned fish is, however, probably hardly appreciable. The canned salmon from the Columbia, however, bring a better price in the market than those from elsewhere. The canners there generally have had a high regard for the reputation of the river, and have avoided canning fall fish or species other than the quinnat. In the Frazer's River the blue-back is largely canned, and its flesh being a little more watery and perhaps paler, is graded below the quinnat. On Puget Sound various species are canned; in fact, everything with red flesh. The best canners on the Sacramento apparently take equal care with their product with those of the Columbia, but they depend largely on the somewhat inferior fall run. There are, however, sometimes salmon canned in San Francisco, which have been in the city markets, and for some reason remaining unsold, have been sent to the canners; such salmon are unfit for food, and canning them should be prohibited.
The fact that the hump-back salmon runs only on alternate years in Puget Sound (1875, 1877, 1879, etc.) is well attested and at present unexplained. Stray individuals only are taken in other years. This species has a distinct "run," in the United States, only in Puget Sound, although individuals (called "lost salmon") are occasionally taken in the Columbia and in the Sacramento.--American Naturalist.
[Footnote: A lecture by Dr. O. J. Lodge, delivered at the London Institution on December 16, 1880.]
Ever since the subject on which I have the honor to speak to you to-night was arranged, I have been astonished at my own audacity in proposing to deal in the course of sixty minutes with a subject so gigantic and so profound that a course of sixty lectures would be quite inadequate for its thorough and exhaustive treatment.
I must indeed confine myself carefully to some few of the typical and most salient points in the relation between electricity and light, and I must economize time by plunging at once into the middle of the matter without further preliminaries.
Now, when a person is setting off to discuss the relation between electricity and light, it is very natural and very proper to pull him up short with the two questions: What do you mean by electricity? and What do you mean by light? These two questions I intend to try briefly to answer. And here let me observe that in answering these fundamental questions, I do not necessarily assume a fundamental ignorance on your part of these two agents, but rather the contrary; and must beg you to remember that if I repeat well-known and simple experiments before you, it is for the purpose of directing attention to their real meaning and significance, not to their obvious and superficial characteristics; in the same way that I might repeat the exceedingly familiar experiment of dropping a stone to the earth if we were going to define what we meant by gravitation.
Now, then, we will ask first, What is electricity? and the simple answer must be, We don't know. Well, but this need not necessarily be depressing. If the same question were asked about matter, or about energy, we should have likewise to reply, No one knows.
But then the term Matter is a very general one, and so is the term Energy. They are heads, in fact, under which we classify more special phenomena.
Thus, if we were asked, What is sulphur? or what is selenium? we should at least be able to reply, A form of matter; and then proceed to describe its properties,i. e., how it affected our bodies and other bodies.
Again, to the question, What is heat? we can reply, A form of energy; and proceed to describe the peculiarities which distinguish it from other forms of energy.
But to the question. What is electricity? we have no answer pat like this. We can not assert that it is a form of matter, neither can we deny it; on the other hand, we certainly can not assert that it is a form of energy, and I should be disposed to deny it. It may be that electricity is an entityper se, just as matter is an entityper se.
Nevertheless, I can tell you what I mean by electricity by appealing to its known behavior.
Here is a battery, that is, an electricity pump; it will drive electricity along. Prof. Ayrtou is going, I am afraid, to tell you, on the 20th of January next, that itproduceselectricity; but if he does, I hope you will remember that that is exactly what neither it nor anything else can do. It is as impossible to generate electricity in the sense I am trying to give the word, as it is to produce matter. Of course I need hardly say that Prof. Ayrton knows this perfectly well; it is merely a question of words,i. e., of what you understand by the word electricity.
I want you, then, to regard this battery and all electrical machines and batteries as kinds of electricity pumps, which drive the electricity along through the wire very much as a water-pump can drive water along pipes. While this is going on the wire manifests a whole series of properties, which are called the properties of the current.
[Here were shown an ignited platinum wire, the electric arc between two carbons, an electric machine spark, an induction coil spark, and a vacuum tube glow. Also a large nail was magnetized by being wrapped in the current, and two helices were suspended and seen to direct and attract each other.]
To make a magnet, then, we only need a current of electricity flowing round and round in a whirl. A vortex or whirlpool of electricity is in fact a magnet; andvice versa. And these whirls have the power of directing and attracting other previously existing whirls according to certain laws, called the laws of magnetism. And, moreover, they have the power of exciting fresh whirls in neighboring conductors, and of repelling them according to the laws of diamagnetism. The theory of the actions is known, though the nature of the whirls, as of the simple stream of electricity, is at present unknown.
[Here was shown a large electro-magnet and an induction-coil vacuum discharge spinning round and round when placed in its field.]
So much for what happens when electricity is made to travel along conductors,i. e., when it travels along like a stream of water in a pipe, or spins round and round like a whirlpool.
But there is another set of phenomena, usually regarded as distinct and of another order, but which are not so distinct as they appear, which manifest themselves when you join the pump to a piece of glass, or any non-conductor, and try to force the electricity through that. You succeed in driving some through, but the flow is no longer like that of water in an open pipe; it is as if the pipe were completely obstructed by a number of elastic partitions or diaphragms. The water can not move without straining and bending these diaphragms, and if you allow it, these strained partitions will recover themselves, and drive the water back again. [Here was explained the process of charging a Leyden jar.] The essential thing to remember is that we may have electrical energy in two forms, the static and the kinetic; and it is, therefore, also possible to have the rapid alternation from one of these forms to the other, called vibration.
Now we will pass to the second question: What do you mean by light? And the first and obvious answer is, Everybody knows. And everybody that is not blind does know to a certain extent. We have a special sense organ for appreciating light, whereas we have none for electricity. Nevertheless, we must admit that we really know very little about the intimate nature of light--very little more than about electricity. But we do know this, that light is a form of energy, and, moreover, that it is energy rapidly alternating between the static and the kinetic forms--that it is, in fact, a special kind of energy of vibration. We are absolutely certain that light is a periodic disturbance in some medium, periodic both in space and time; that is to say, the same appearances regularly recur at certain equal intervals of distance at the same time, and also present themselves at equal intervals of time at the same place; that in fact it belongs to the class of motions called by mathematicians undulatory or wave motions. The wave motion in this model (Powell's wave apparatus) results from the simple up and down motion popularly associated with the term wave. But when a mathematician calls a thing a wave he means that the disturbance is represented by a certain general type of formula, not that it is an up-and-down motion, or that it looks at all like those things on the top of the sea. The motion of the surface of the sea falls within that formula, and hence is a special variety of wave motion, and the term wave has acquired in popular use this signification and nothing else. So that when one speaks ordinarily of a wave or undulatory motion, one immediately thinks of something heaving up and down, or even perhaps of something breaking on the shore. But when we assert that the form of energy called light is undulatory, we by no means intend to assert that anything whatever is moving up and down, or that the motion, if we could see it, would be anything at all like what we are accustomed to in the ocean. The kind of motion is unknown; we are not even sure that there is anything like motion in the ordinary sense of the word at all.
Now, how much connection between electricity and light have we perceived in this glance into their natures? Not much, truly. It amounts to about this: That on the one hand electrical energy may exist in either of two forms--the static form, when insulators are electrically strained by having had electricity driven partially through them (as in the Leyden jar), which strain is a form of energy because of the tendency to discharge and do work; and the kinetic form, where electricity is moving bodily along through conductors or whirling round and round inside them, which motion of electricity is a form of energy, because the conductors and whirls can attract or repel each other and thereby do work.
And, on the other hand, that light is the rapid alternation of energy from one of these forms to the other--the static form where the medium is strained, to the kinetic form when it moves. It is just conceivable, then, that the static form of the energy of light iselectrostatic, that is, that the medium iselectricallystrained, and that the kinetic form of the energy of light iselectro-kinetic, that is, that the motion is not ordinary motion, but electrical motion--in fact, that light is an electrical vibration, not a material one.
On November 5, last year, there died at Cambridge a man in the full vigor of his faculties--such faculties as do not appear many times in a century--whose chief work has been the establishment of this very fact, the discovery of the link connecting light and electricity; and the proof--for I believe it amounts to a proof--that they are different manifestations of one and the same class of phenomena--that light is, in fact, an electro-magnetic disturbance. The premature death of James Clerk-Maxwell is a loss to science which appears at present utterly irreparable, for he was engaged in researches that no other man can hope as yet adequately to grasp and follow out; but fortunately it did not occur till he had published his book on "Electricity and Magnetism," one of those immortal productions which exalt one's idea of the mind of man, and which has been mentioned by competent critics in the same breath as the "Principia" itself.
But it is not perfect like the "Principia;" much of it is rough-hewn, and requires to be thoroughly worked out. It contains numerous misprints and errata, and part of the second volume is so difficult as to be almost unintelligible. Some, in fact, consists of notes written for private use and not intended for publication. It seems next to impossible now to mature a work silently for twenty or thirty years, as was done by Newton two and a half centuries ago. But a second edition was preparing, and much might have been improved in form if life had been spared to the illustrious author.
The main proof of the electro-magnetic theory of light is this: The rate at which light travels has been measured many times, and is pretty well known. The rate at which an electro-magnetic wave disturbance would travel if such could be generated (and Mr. Fitzgerald, of Dublin, thinks he has proved that it can not be generated directly by any known electrical means) can be also determined by calculation from electrical measurements. The two velocities agree exactly. This is the great physical constant known as the ratio V, which so many physicists have been measuring, and are likely to be measuring for some time to come.
Many and brilliant as were Maxwell's discoveries, not only in electricity, but also in the theory of the nature of gases, and in molecular science generally, I can not help thinking that if one of them is more striking and more full of future significance than the rest, it is the one I have just mentioned--the theory that light is an electrical phenomenon.
The first glimpse of this splendid generalization was caught in 1845, five and thirty years ago, by that prince of pure experimentalists, Michael Faraday. His reasons for suspecting some connection between electricity and light are not clear to us--in fact, they could not have been clear to him; but he seems to have felt a conviction that if he only tried long enough and sent all kinds of rays of light in all possible directions across electric and magnetic fields in all sorts of media, he must ultimately hit upon something. Well, this is very nearly what he did. With a sublime patience and perseverance which remind one of the way Kepler hunted down guess after guess in a different field of research, Faraday combined electricity, or magnetism, and light in all manner of ways, and at last he was rewarded with a result. And a most out-of-the-way result it seemed. First, you have to get a most powerful magnet and very strongly excite it; then you have to pierce its two poles with holes, in order that a beam of light may travel from one to the other along the lines of force; then, as ordinary light is no good, you must get a beam of plane polarized light, and send it between the poles. But still no result is obtained until, finally, you interpose a piece of a rare and out-of-the-way material, which Faraday had himself discovered and made--a kind of glass which contains borate of lead, and which is very heavy, or dense, and which must be perfectly annealed.
And now, when all these arrangements are completed, what is seen is simply this, that if an analyzer is arranged to stop the light and make the field quite dark before the magnet is excited, then directly the battery is connected and the magnet called into action, a faint and barely perceptible brightening of the field occurs, which will disappear if the analyzer be slightly rotated. [The experiment was then shown.] Now, no wonder that no one understood this result. Faraday himself did not understand it at all. He seems to have thought that the magnetic lines of force were rendered luminous, or that the light was magnetized; in fact, he was in a fog, and had no idea of its real significance. Nor had any one. Continental philosophers experienced some difficulty and several failures before they were able to repeat the experiment. It was, in fact, discovered too soon, and before the scientific world was ready to receive it, and it was reserved for Sir William Thomson briefly, but very clearly, to point out, and for Clerk-Maxwell more fully to develop, its most important consequences. [The principle of the experiment was then illustrated by the aid of a mechanical model.]
This is the fundamental experiment on which Clerk-Maxwell's theory of light is based; but of late years many fresh facts and relations between electricity and light have been discovered, and at the present time they are tumbling in in great numbers.
It was found by Faraday that many other transparent media besides heavy glass would show the phenomenon if placed between the poles, only in a less degree; and the very important observation that air itself exhibits the same phenomenon, though to an exceedingly small extent, has just been made by Kundt and Rontgen in Germany.
Dr. Kerr, of Glasgow, has extended the result to opaque bodies, and has shown that if light be passed through magnetizedironits plane is rotated. The film of iron must be exceedingly thin, because of its opacity, and hence, though the intrinsic rotating power of iron is undoubtedly very great, the observed rotation is exceedingly small and difficult to observe; and it is only by a very remarkable patience and care and ingenuity that Dr. Kerr has obtained his result. Mr. Fitzgerald, of Dublin, has examined the question mathematically, and has shown that Maxwell's theory would have enabled Dr. Kerr's result to be predicted.
Another requirement of the theory is that bodies which are transparent to light must be insulators or non-conductors of electricity, and that conductors of electricity are necessarily opaque to light. Simple observation amply confirms this; metals are the best conductors, and are the most opaque bodies known. Insulators such as glass and crystals are transparent whenever they are sufficiently homogeneous, and the very remarkable researches of Prof. Graham Bell in the last few months have shown that evenebonite, one of the most opaque insulators to ordinary vision, is certainly transparent to some kinds of radiation, and transparent to no small degree.
[The reason why transparent bodies must insulate, and why conductors must be opaque, was here illustrated by mechanical models.]
A further consequence of the theory is that the velocity of light in a transparent medium will be affected by its electrical strain constant; in other words, that its refractive index will bear some close but not yet quite ascertained relation to its specific inductive capacity. Experiment has partially confirmed this, but the confirmation is as yet very incomplete. But there are a number of results not predicted by theory, and whose connection with the theory is not clearly made out. We have the fact that light falling on the platinum electrode of a voltameter generates a current, first observed, I think, by Sir W. R. Grove--at any rate, it is mentioned in his "Correlation of Forces"--extended by Becquerel and Robert Sabine to other substances, and now being extended to fluorescent and other bodies by Prof. Minchin. And finally--for I must be brief--we have the remarkable action of light on selenium. This fact was discovered accidentally by an assistant in the laboratory of Mr. Willoughby Smith, who noticed that a piece of selenium conducted electricity very much better when light was falling upon it than when it was in the dark. The light of a candle is sufficient, and instantaneously brings down the resistance to something like one-fifth of its original value.
I could show you these effects, but there is not much to see; it is an intensely interesting phenomenon, but its external manifestation is not striking--any more than Faraday's heavy glass experiment was.
This is the phenomenon which, as you know, has been utilized by Prof. Graham Bell in that most ingenious and striking invention, the photophone. By the kindness of Prof. Silvanus Thompson, I have a few slides to show the principle of the invention, and Mr. Shelford Bidwell has been kind enough to lend me his home-made photophone, which answers exceedingly well for short distances.
I have now trespassed long enough upon your patience, but I must just allude to what may very likely be the next striking popular discovery; and that is the transmission of light by electricity; I mean the transmission of such things as views and pictures by means of the electric wire. It has not yet been done, but it seems already theoretically possible, and it may very soon be practically accomplished.
During the last six years Dr. Warren de la Rue has been investigating, in conjunction with Dr. Hugo Muller, the various and highly interesting phenomena which accompany the electric discharge. From time to time the results of their researches were communicated to the Royal Society, and appeared in its Proceedings. Early last year Dr. De la Rue being requested to bring the subject before the members of the Royal Institution, acceded to the pressing invitation of his colleagues and scientific friends. The discourse, which was necessarily long postponed on account of the preparations that had to be made, was finally given on Friday, the 21st of January, and was one of the most remarkable, from the elaborate nature of the experiments, ever delivered in the theater of that deservedly famous institution.
Owing to the great inconvenience of removing the battery from his laboratory, Dr. de la Rue, despite the great expenditure, directed Mr. S. Tisley to prepare, expressly for the lecture, a second series of 14,400 cells, and fit it up in the basement of the Royal Institution. The construction of this new battery occupied Mr. Tisley a whole year, while the charging of it extended over a fortnight.
The "de la Rue cell," if we may so call one of these elements, consists of a zinc rod, the lower portion of which is embedded in a solid electrolyte, viz., chloride of silver, with which are connected two flattened silver wires to serve as electrodes. When these are united and the silver chloride moistened, chemical action begins, and a weak but constant current is generated.
The electromotive force of such a cell is 1.03 volts, and a current equivalent to one volt passing through a resistance of one ohm was found to decompose 0.00146 grain of water in one second. The battery is divided into "cabinets," which hold from 1,200 to 2,160 small elements each. This facilitates removal, and also the detection of any fault that may occur.
It will be remembered that in 1808 Sir Humphry Davy constructed his battery of 2,000 cells, and thus succeeded in exalting the tiny spark obtained in closing the circuit into the luminous sheaf of the voltaic arc. He also observed that the spark passed even when the poles were separated by a distance varying from 1/40 to 1/30 of an inch. This appears to have been subsequently forgotten, as we find later physicists questioning the possibility of the spark leaping over any interpolar distance. Mr. J. P. Gassiot, of Clapham, demonstrated the inaccuracy of this opinion by constructing a battery of 3,000 Leclanché cells, which gave a spark of 0.025 inch; a similar number of "de la Rue" cells gives an 0.0564 inch spark. This considerable increase in potential is chiefly due to better insulation.
The great energy of this battery was illustrated by a variety of experiments. Thus, a large condenser, specially constructed by Messrs. Varley, and having a capacity equal to that of 6,485 large Leyden jars, was almost immediately charged by the current from 10,000 cells. Wires of various kinds, and from 9 inches to 29 inches in length, were instantly volatilized by the passage of the electricity thus stored up. The current induced in the secondary wire of a coil by the discharge of the condenser through the primary, was also sufficiently intense to deflagrate wires of considerable length and thickness.
It was with such power at his command that Dr. De la Rue proceeded to investigate several important electrical laws. He has found, for example, that the positive discharge is more intermittent than the negative, that the arc is always preceded by a streamer-like discharge, that its temperature is about 16,000 deg., and its length at the ordinary pressure of the atmosphere, when taken between two points, varies as the square of the number of cells. Thus, with a battery of 1,000 cells, the arc was 0.0051 inch, with 11,000 cells it increased to 0.62 inch. The same law was found to hold when the discharge took place between a point and a disk; it failed entirely, however, when the terminals were two disks.
It was also shown that the voltaic arc is not a phenomenon of conduction, but is essentially a disruptive discharge, the intervals between the passage of two successive static sparks being the time required for the battery to collect sufficient power to leap over the interposed resistance. This was further confirmed by the introduction of a condenser, when the intervals were perceptibly larger.
Faraday proved that the quantity of electricity necessary to produce a strong flash of lightning would result from the decomposition of a single grain of water, and Dr. de la Rue's experiments confirm this extraordinary statement. He has calculated that this quantity of electricity would be 5,000 times as great as the charge of his large condenser, and that a lightning flash a mile long would require the potential of 3,500,000 cells, that is to say, of 243 of his powerful batteries.
In experimenting with "vacuum" tubes, he has found that the discharge is also invariably disruptive. This is an important point, as many physicists speak and write of the phenomenon as one of conduction. Air, in every degree of tenuity, refuses to act as a conductor of electricity. These experiments show that the resistance of gaseous media diminishes with the pressure only up to a certain point, beyond which it rapidly increases. Thus, in the case of hydrogen, it diminishes up to 0.642 mm., 845 millionths; it then rises as the exhaustion proceeds, and at 0.00065 mm., 8.6 millionths, it requires as high a potential as at 21.7 mm., 28.553 millionths. At 0.00137 mm., 1.8 millionth, the current from 11,000 cells would not pass through a tube for which 430 cells sufficed at the pressure of minimum resistance. At a pressure of 0.0055 mm., 0.066 millionth, the highest exhaust obtained in any of the experiments, even a one-inch spark from an induction coil refused to pass. It was also ascertained that there is neither condensacian nor dilatation of the gas in contact with the terminals prior to the passage of the discharge.
These researches naturally led to some speculation about the conditions under which auroral phenomena may occur. Observers have variously stated the height at which the aurora borealis attains its greatest brilliancy as ranging between 124 and 281 miles. Dr. de la Rue's conclusions fix the upper limit at 124 miles, and that of maximum display at 37 miles, admitting also that the aurora may sometimes occur at an altitude of a few thousand feet.
The aurora was beautifully illustrated by a very large tube, in which the theoretical pressure was carefully maintained, the characteristic roseate tinge being readily produced and maintained.
In studying the stratifications observed in vacuum tubes, Dr. de la Rue finds that they originate at the positive pole, and that their steadiness may be regulated by the resistance in circuit, and that even when the least tremor cannot be detected by the eye, they are still produced by rapid pulsations which may be as frequent as ten millions per second.
Dr. de la Rue concluded his interesting discourse by exhibiting some of the finest tubes of his numerous and unsurpassed collection.--Engineering