Chapter 5

b. indicates blue sky—c. detached clouds—r. rain—v. visibility of objects—q. squalls—w. wet dew—u. ugly threatening appearance—g. gloomy weather.

The exact counterpart of the first norther may be observed with us every fall. On the 30th January, with a rising thermometer and falling barometer, there was rain at midday. The night following was moist—the next day, about tenA.M., the wind came out N. W., with squalls and gloomy weather, a falling thermometer, and rising barometer.

The norther of Feb. 14th differed from the other only in regard to the time of the day when it commenced; the order of events was the same. The rain fell in the night—it cleared off early in the day, and the norther followed in the afternoon. This also is frequently the case with us, as every one may observe.

This brief notice of the surface winds of our climate would be incomplete without a description of those of the thunder-gust and tornado.

The former is exceedingly simple. The showers, which are accompanied with much wind, form suddenly in hot weather, and have a considerable advance condensation (frequently with obvious lateral internal action), extending eastwardly from the line of smooth cloud from which the rain is falling, or rather where the falling rain obscures the inequalities of the cloud.The gust is never felt until the advancing condensation has passed over us, when it takes the place of the gentle easterly breeze which previously set toward the shower.The gust ceases as soon as the cloud has passed.It is obviously the result of the inducing and attracting influence of the cloud upon the atmosphere near the surface of the earth as it passes over it. Let the reader watch attentively thisadvance condensation, from its eastern edge to the line of smooth cloud and falling rain, and he will understand at a glance this internal action of gust-clouds. The whole phenomena are simple and intelligible. A cloud approaching from a westerly point, dark and irregular from its eastern edge to the line of falling rain, where it appears smooth and of a light color; wind from the east blowing gently toward it, till the condensation is over us; then the gust following the cloud; then the rain, and in a few minutes the cloud, and wind, and rain have passed on to the east, and “sunshine” returns.

The tornado, as it is termed when it occurs upon land, “spout,” if on the water, is sometimes of a different character, and as it undoubtedly had great influence in inducing the gyrating theory of Mr. Redfield, and the aspiratory theory of Mr. Espy, and has been cited by both in support of their respective theories, it deserves a more particular notice. There are several marked peculiarities attending it which determine its character.

1st. It occurs during apeculiarly sultry and electricstate of the trade and surface atmosphere, and at a time when thunder showers are prevailing in and around the locality, and at every period of the year when such a state of the atmosphere exists. One recently occurred in Brandon, Ohio, in midwinter.

2d. There is always a cloud above, but very near the earth, between which and the earth the tornado forms and rages. It is usually described as a black cloud, ranging about 1000 feet or less above theearth, often with a whitish shaped cone projecting from it, and forming a connection with the earth; at intervals rising and breaking the connection, and again descending and renewing it with devastating energy. Its width at the surface varies from forty to one hundred and eighty rods—the most usual width being from sixty to ninety rods. Sometimes when still wider, they have more the character of thunder-gusts, and are brightly luminous.

3d. Two motions are usually visible, one ascending one near the earth and in the middle, and a gyratory one around the other. The latter is rarely felt, or its effects observed, near the earth. Occasionally, and at intervals, objects are thrown obliquely backward by it.

4th. It is composed, at the surface of the earth, oftwo lateral currents, a northerly and southerly one, varying in direction, but normally at right angles in most cases, although not always, with its course of progression, extending from the extreme limits of its track to the axis; which currents are most distinctly defined toward the center, and upward. These currents prostrate trees, or elevate and remove every thing in their way which is detached and movable. There does not seem to be any current in advance of these lateral ones tending toward the tornado, save in rare and excepted cases, and then owing to the make of the ground or the irregular action of the currents; nor any following, except that made by the curving of the lateral currents toward the center of the spout as it moves on, and perhapsa tendency of the air to follow and supply the place of that which has been carried upward and forward, like that of water following the stern of a vessel. The south current is always the strongest, and often a little in advance of the other, and covers the greatest area. The proportion of the two currents to each other is much the same that the S. E. trades bear to the N. E. This excess in volume and strength of the southerly current will explain the irregularities in most cases, and the fact that objects are so oftentaken up and carried from the south to the north side, and so rarely from the north and carried south of the axis. These irregularities are such as attend all violent forces, and something can be found which will favor almost any theory; but the two lateral currents appear always to be the principal actors, except, perhaps, when it widens out and assumes more the character of a straightforward gust. See a collection by Professor Loomis, American Journal of Science, vol. xliii. p. 278.

The following diagram is a section of the New Haven tornado, from Professor Olmstead’s map accompanying his article in the “American Journal of Science and Art,” vol. 37. p. 340.

The manner in which the main currents flow is shown by their early and unresisted effect in a cornfield, as represented by the dotted lines. The direction in which the fragments of buildings were carried by the greater power of the southerly currents is shown also. And so is this irregular action, where a part of the southerly current broke through thenortherly one, and prostrated two or three trees backward on the north side of the axis.

Fig. 16.

5th. This cloud, and its spout, move generally with the course of the counter-trade in the locality—i. e., from some point between S. W. and W., to the eastward, but occasionally a little south of east, deflected by the magnetic wave beneath the belt of showers.

6th. Several exceedingly instructive particulars have been observed and recorded.

a.No wind is felt outside of the track, as those assert who have stood very near it, and its effects show.

b. The track is often as distinctly marked, where it passed through a wood, as if the grubbers had been there with their axes to open a path for a rail-road. The branches of the trees, projecting within its limits,are found twisted and broken off, or stripped of their leaves, while not a leaf is disturbed at the distance of a foot or two on the opposite side of the tree, and outside of the track.

c. As the spout passes over water, the latter seems toboil upandrise to meet it, andflow upits trunk in acontinued stream.

d. As it passes over the land, and over buildings, fences, and other movable things, they appear toshoot up, instantaneously, as it were, into the air, and into fragments. If buildings are not destroyed or removed, the doors may be burst openon the leeward side, and gable endssnatched out, and roofs taken off on thesame side, while that portion of the building which is to the windward remains unaffected.

e. Articles of clothing, and other light articles, have been carried out of buildings through open doors, or chimneys, or holes made in the roofs, and to a great distance, withoutany openingbeing made for the air toblowin.

f. If there be a discharge of electricity up the spout from the earth, like that of lightning, the intense action ceases for a time or entirely.

g. Vegetation in the track is often scorched and killed, and so of the leaves on one side of a tree, which is within the track, while those on the other side, and without the track remain unaffected. (Espy’s Philosophy of Storms, 359, cited from Peltier.)

h. The active agent whatever it is, has been known toseize hold of a chain attached to a plowanddraw the plow about, turning the stiff sod for a considerabledistance. (See Loomis on the tornado at Stow, Ohio, American Journal of Science, vol. xxxiii. p. 368.)

i. In passing over ponds, the spout has taken up all the water and fish, and scattered them in every direction, and to a great distance.

j. The barometer falls very little during the passage of the spout. (See the Natchez hurricane of 1827, Espy page 337.) Not more than itfrequentlydoes during gentle showers.

k. Persons have been taken up, carried some distance, and if not projected against some object in the way, or some object against them, have usually beenset down gently and uninjured.

l. Buildings which stood upon posts, with a free passage for the air under them, although in the path of the tornado, escaped undisturbed. (Olmstead’s account of the New Haven tornado, American Journal of Science, vol. xxxvii. p 340.)

m. A chisel taken from a chest of tools, and stuck fast in the wall of the house. (Ibid.)

n. Fowls have had all their feathers stripped from them in an instant and run about naked but uninjured.[5]

o. Articles of furniture, etc., have been found torn in pieces by antagonistic forces.

p. Frames taken from looking-glasses without breaking the glass. Nails drawn from the roofs of houses without disturbing the tiles.

q. Hinges taken from doors—mud taken from the bed of a stream(the water being first removed), and let down on a house covering it completely—a farmer taken up from his wagon and carried thirty rods, his horses carried an equal distance in another direction,the harness stripped from them, and the wagon carried off also,one wheel not found at all. (American Journal of Science, vol. xxxvii. p. 93.)

Pieces of timber, boards, and clapboard, driven into the side of a hill,as no force of powder could drive them, etc., etc.

Now to my mind, these circumstances indicate clearly, that it is not wind,i. e., mere currents of air, which produces the effect, but that acontinuous currentorstream of electricityfrom the earth to the cloud exists, and carries with it from near the earth, such articles as are movable: That this stream collects from thenortherlyandsoutherlyside upon themagnetic meridian, intwo currentswithpolarity, which meet in their passage up at the center; curving toward the center in the posterior part as the spout moves on, when acting in a normal manner, and making the “law of curvature” observed: That no conceivable movement of the air alone in such limited spaces could produce such effects; or if so, that no agent but electricity could so move the air: That the air in a building could not shoot the roof upward, and into fragments; much less could the air in a cellar by any conceivable force, be made to elevateor shoot upthe entire house, and its inmates, and contents—effects so totally unlike what takesplace in gales, hurricanes, and typhoons: That elastic free air never did nor could take hold of the plow chain, and plow up the ground; or scorch and kill the vegetation; or twist thelimbsfrom one side of a tree, while the most delicate leaves on the other, and within two or three feet, remained unaffected and undisturbed; or pick the chickens: That even if the expansion of the air could produce these effects—if a sudden vacuum were produced—nothing but currents of electricity could produce the sudden vacuum, by removing the air above.

It is well settled that atmospheric electricity can and does flow in currents with light, by experiments in relation to the brush discharge, etc. That it may do so without light or disruptive discharge, and in a stream, or as it is termed, by convection, with the force and effect seen in the tornado, is perfectly consistent with what we know of it—and it is, I think clearly evinced that such is the character of the phenomena, by the fact that a sudden powerfuldisruptivedischarge,with light, up the spout, produces an instantaneous partial or total suspension of its action; to be renewed as the cloud passes overanotherand more highly chargedportionof theearth’s surface. Peltier gives instances where the spout has been entirely and instantaneously destroyed by such a sudden and powerful discharge of electricity; marking the spot where it was so destroyed by a large hole in the earth, from which the discharge issued. And in fact these tornados are often steadily luminous,and so much so, when they occur in the night, as to enable persons to read without difficulty.

The lateral inward and upward currents, are accompanied, after they meet and unite, or seem to unite, by gyratory or circular ones. How are they produced? This question can only be answered by analogy. No permanent impressions are left by the circular currents, except to a limited extent, and in occasional instances; and observation of them has been, and must necessarily be limited and uncertain. I have witnessed one or two on a moderate scale; but owing to the suddenness of their passage, and the confusion of the objects taken up, it was difficult to determine what the circular currents were. When the southerly current is much the strongest, it appears sometimes to cross the axis, and curve round the northerly one. Perhaps this may be all the curving that really takes place, except at the posterior part of the axis, for evidence of a curving on the south of the axis is rarely, if ever seen.

Assuming, however, that the main currents unite and form one from the earth to the cloud,inducedcircular currents would be in perfect keeping with the known laws of electricity. Such currents, and with magnetic properties, are always induced by powerful currents of voltaic electricity passing through wires. And doubtlessin all casespowerful currents of electricityinduce attendant circular currents. This may account for the external gyration of the spout.

Or it may be that the two lateral currents of airwhich attend the currents of electricity, do not unite; having opposite polarity, but pass by and around each other, in connection with the circular magnetic currents. Future observation and perhaps experimental research will determine this. But it may not be accomplished by the present generation; for the belief that tornados are mere whirlwinds, produced by the action of the sun in heating the land, is adhered to, notwithstanding they cross the intense magnetic area of Ohio in mid-winter, and seems to be ineradicable.

The proportions of different winds vary in different localities. For the benefit of those who are curious, I copy a table from an able compilation by Professor Coffin, published by the Smithsonian Institute, showing the proportion of the winds at New Haven (the station nearest to me). It will be noticed that during the year the N. W. winds blow the greatest number of days; the S. W. next; the N. E. and S. E. less than either, and about equal. It may be observed that the two latter bear about the same proportion to the whole, that our number of cloudy and stormy days, averaging about ninety, bear to the whole number of days in the year.

This work of Mr. Coffin has been brought to my notice since the foregoing pages were written. The facts embodied in it will be found to comport with what I have observed and stated. In relation to the proportionate number of days in the year during which the wind blows from the different points of the compass at the several stations it is very full and able.

But it has cardinal defects. It does not show themain currentsof the atmosphere. It treats the surface-winds, which are incidental, as principals. The direction of the main currents is indeed shown frequently by the mean course of the surface winds, but not uniformly or intelligibly. Nor does it distinguish between the fair weather and storm winds; nor always between the trade winds during their northern transit, and the variable winds north of the trade-wind region. Hence, the deductions derived from it disclose no general system, and sustain no theory, although many very important facts appear. Some of these, Professor Coffin found it difficult to reconcile with received theories, or satisfactorily explain. For instance, he found the prevailing winds of the United States, in Louisiana and Texas, S. and S. E.; in western Arkansas, and Missouri, southerly, and in Iowa and Wisconsin, S. W., forming a curve, and evidently connected together.

Thus, alluding to the winds west of the Mississippi, and between the parallels of 36° and 60°, he says:

“On the American continent, west of the Mississippi, there appears to be more diversity in the mean direction of the wind, yet here it iswesterly at sixteen stations out of twenty, from which observations have been obtained. The most peculiar feature in this region, is thelineof southerly winds on the western borders of Arkansas and Missouri. It seems to form a connecting link between the winds of this zone and the south-easterly ones that we find south of it; and, in some degree, to favor an idea that has been advanced, that there is a vast eddy, extending from the western shore of the Gulf of Mexico, to the eastern shore of the Atlantic; that the easterly trade-winds of the Atlantic Ocean, when they strike the American continent, veer northwardly, and then N. E., and thus recross the Atlantic, and follow down the coast of Portugal and Africa, till they complete the circuit.”

This mean prevalence of the curving winds indicates the course of the western portion of the concentrated counter-trade, of which we have so fully spoken, and to which that portion owes its rains and fertility. Doubtless the curve would have been traced somewhat further west, if observations had been obtained from more westerly stations.

The idea of an eddy, to which Professor Coffin alludes, is of course unsound; that of a counter-trade, most fully confirmed; the curve corresponding with that of the regular rains and fertility as they are known to exist.

Professor Coffin is a believer in the generally-received theory of rarefaction, as the cause of all winds. His work is published by the Smithsonian Institution, and the theory is, so far forth, nationalized. But he found it very difficult to reconcile all the facts he obtained, with the theory, and, possessing a truth-loving mind, he frankly admits it. Alluding to the prevalence of N. E. winds off the coast of Africa in the summer months, as shown by certain numbered wind-roses, he says:

“Nos. 81, 83, 86, and 91, have caused me much perplexity. The arrows for the warmer months evidently indicate a point of rarefaction situated to thesouthorsouth-west, and yet all the observations from which they were computed were taken within a few hundred miles of the African coast and desert of Sahara; a region, the annual range of whose temperature must be exceedingly great. The only way in which I can account for a fact so astonishing, is, by supposing the deflecting forces at these numbers to be secondary to the influence which we see so strongly marked in Nos. 88, 89, and 90. Let us, then, first devote our attention to these.”

(We have not space for the map of Professor Coffin, nor is it necessary to insert it. The numbers 81, 83, 86, and 91, refer to respective portions of the Atlantic, west of Africa, North of the Cape de Verdes, of 5° of latitude each, where the N. E. trades are drawing off from the coast. The Nos. 88, 89, and 90 refer to like portionsbelowthe Cape de Verde, where the S. W. monsoons are found under the rainy belt; and the explanation of the distinguished author is an attempt to account for the blowing of the tradesfromSahara, by supposing them connected with the monsoons further south, which seem to blow toward it.)

“The intense heat of the Great Desert rarefies the air exceedingly from June to October, inclusive, and hence the arrows of unparalleled length (Plate XII.),” (showing the monsoon winds below the Cape de Verdes,) “pointing toward it during those months, the longest being longer than that which represents the most uniform of the trade-winds, in the ratio of 104 to 89. The influence of this rarefaction is sufficient to curve the powerful current of the trade-winds in the manner exhibited on Plate VII. Nos. 89 and 90, and to produce the not less remarkable change in No. 88, holding the current back and retarding it, so that its progressive motion in thethreemonths of July, August, and September united, hardly exceeds that during anyoneof the colder months of the year. But while this is so, the trades on the western side of the Atlantic are pursuing nearly their regular track, being butslightly affected by these influences. As a consequence, the latter must leave, as it were, a partial vacuum behind them, which is filled by air flowing in from the north-east and south-east. This will account for the seeming anomaly of having a somewhat strong deflecting force directed toward mid-ocean, in the hottest part of the year, as in the numbers above referred to.And yet it may be very naturally asked, Why does not the air from these parts supply the Great Desert directly, instead of taking a circuitous route to supply the region that supplies it? A question which, I confess, it seems difficult to answer.”

(The italicization in the foregoing extract is mine).

Here the worthy professor finds a fact inconsistent with the theory of rarefaction—viz.: that the winds blow off shore, and toward mid-ocean, opposite Sahara, and he is “perplexed and astonished.” The theory, however, must be maintained, and one of those modifying hypotheses which have made meteorology such a complicated piece of patch-work, must be invented; some “deflecting forces” found. There is the Great Desert, bordering upon the ocean, north of the Cape de Verde Islands, for a distance of six hundred miles, widening as it extends inland, whose temperature, as he says, “must be exceedingly great;” and doubtless is so, and yet the air, instead of blowing in upon it in a hurricane, is actually drawing off from it, and blowing towards the S. W., where the water and air do not rise above 84°. Well may he be “perplexed and astonished.”

Turning south, however, to the distance of five hundred miles or more, he finds the S. W. monsoon winds, which in those months blow under the belt of rains, toward the land, in the direction of, but at a great distance from, Sahara. It is an easy matterto suppose that they reach the Great Desert and supply its vortex of rarefaction, inasmuch as they blow in a direction toward it, and distance is no impediment to supposition.

Then it is necessary tosupposethat the S. E. and N. E. trades, at the south-west, draw so strongly to the westward as to create a partial vacuum to the S. W. of Sahara, which is filled by the winds which draw off shore, and then we have the supply brought from the distance of five hundred miles or more, by an ascending vortex, which creates a vacuum, and the air near the vortex taken away inanotherdirection by apartialvacuum; and so an ascendingvortex, which creates a vacuum is supplied from a distance, and apartial vacuumat a distance is supplied by the air near the perfect vacuum. Such an idea of a supply by a circuitous route, and secondary influence, is not very philosophical, to say the least, and Professor Coffin feels it; and to the question, Why is it so? which, he says, may very naturally be asked, he confesses there is no answer. And there would be none, even if his suppositions were based upon facts. But other questions might be asked equally difficult to be answered, viz.:

1st. Is there any rarefaction which can draw the trades to the west, and in that particular locality, in opposition to the supposed vortex of Sahara, by creating apartial vacuum?

2d. Are they in fact so drawn?

3d. Do the S. W. winds, south of the Cape de Verdes, andunder the rainy belt, which in the summermonths extend up to these islands,reach the desert at all?

These are pertinent questions,and every one of them must be answered in the negative. The hypothesis is without foundation, and Professor’s Coffin’s perplexity and astonishment must remain, until he abandons the theory of rarefaction entirely. The winds which so perplex him are nothing but the regular N. E. trades, made to originate on the coast and continent of Africa, in summer, by the northern transit of the whole machinery. They not only draw off from the desert coast, but theyblow over the desert itselfon to the ocean, and into the rainy belt upon the land, as we have already seen, and the supposed vortex of rarefaction does not exist.

That the monsoons do not reach the desert is demonstrated by the tables of Professor Coffin, and to set it at rest we will make the necessary extracts. Commencing with the region from the equator to 5° N., and from 10° to 55° W. longitude, we have the observed winds in proportion, as follows, for July and August—the south-east trades prevailing, inasmuch as the belt of rains is at this season situated further north.

Latitude 0° To 5°, Longitude From Greenwich 10° To 55°.

Here, it is evident that the S. E. trades are the prevailing winds, but their course is variable.

Ascending to the region between 5° and 10° north latitude, and 10° to 55° west longitude, the northern part of which at this season is covered by the rainy belt; we find the monsoon, the S., S. S. W., and S. W. winds, the prevailing ones in August, although the winds are variable, as usual under the rainy belt.

Ascending to the region of 10° to 15° north latitude, and 15° to 45° west longitude, we find the winds exceedingly variable, and the monsoons diminished remarkably. If Professor Coffin’s theory was correct, they should increase as they approach the desert; but they in fact, diminish, and the N. E. trades are found at the north portion.

Ascending to the region between 15° and 20° north latitude, and 15° to 45° west longitude, we get north of the belt of rainsand lose the monsoons entirely although still below the desert; and find the regular N. E. trades, with less variable winds than are found in almost any other part of the ocean.

Ascending still further to the region between 20° and 25° north latitude, and 15° and 45° west longitude, which borders, in part, on the S. W. corner of the desert, and we have not, during the month of August, a single wind between S. S. E. and W. N. W., which blows in upon the land; andonly twelve instances out of three hundred and ninety-four in this hottest month in the year, and on the southern portion of the desert, when the wind blows on shore from any quarter. This is demonstration. The monsoon winds are confined to the rainy belt; they do not reach the desert, nor does the desert attract the winds from the ocean, or reverse, hold back, or disturb the trades.

Ascending once more, to the region between the degrees of 25 and 30, north latitude, and 15 and 45, west longitude, we find it bounded east entirely on the center of the desert. Now here, certainly, there must be evidence of the truth of the rarefaction theory, if any where on the face of the earth. Yet here, in July and August, we find the trades as regular as any where, and not more variable winds than are found in the trades toward their northern limits every where, and in August, only forty out of four hundred and twenty-nine winds, blowing directly or indirectly on shore.

It would seem to be impossible for any man to believe in the theory of rarefaction, after an examination of these tables.

Professor Coffin discovers other anomalies, for which he finds it difficult to account. Among these are the northerly tendency, in the afternoon, of the winds in Ohio, south of Lake Erie; the winds of south-western Asia, which, he says, “Are so irregular as to defy all attempts to reduce them to system;” particularizing the N. W. at Jerusalem, the westerly at Bagdad, the N. E. at Constantinople, the northerly at Trebizond, etc., etc. Jerusalem has the Mediterranean at the N. W., Bagdad has it at the west, Constantinople has the Black Sea at the N. E., Trebizond N. N. W. and N. E., and the counter-trade, as it passes over them, draws its storm-surface wind or sea-breeze, from the quarter where evaporation is greatest, and the atmosphere is most susceptible of electrical inductive influence. Precisely as it draws from the ocean and the eastward, east of the Alleghanies, from the lake region, west of the lakes, and from the northward, south of the lakes, and from the westward, east of them.

This law of attraction will explain, too, the mean prevalence of easterly winds north of the parallel of 60°, at the stations named in his work. Great Bear Lake, Great Slave Lake, and Fort Enterprise, lie east of the Rocky Mountain range which interposes between them and the Pacific, and have Hudson’s Bay and other large bodies of water on the east and north. Hence, easterly winds prevail at these places. At Norway House, on Nelson’s River, near the north end of Lake Winnipeg, a large body of water, which stretches off to the south, we find the south wind theprevalent one, especially in December, when the northern and north-eastern waters are frozen up, and the N. E. largely present at all seasons of the year.

At New Hernhut, in winter, when Davis’ Straits are covered with floes, the prevailing wind is east, drawn from the warm, open sea east of Greenland, where the Gulf Stream is evaporating. But in June and July, when evaporation is going on over Davis’ Straits and Baffin’s Bay, the prevailing winds are west and south, and the east winds fall off.

Other stations are equally instructive, but I must forbear.

In relation, however, to the easterly zone of wind, of which Professor Coffin speaks, it should be added that the counter-trade, south of the magnetic pole, in high latitudes, pursues an easterly course, is near the earth, and attracts an opposite wind as it does on the east and north of the pole, in localities where the surface atmosphere is not peculiarly susceptible to its influence, and, therefore, thewinds are mainly opposite to its course. Thus, at Melville Island, they are almost all westerly and north-westerly, for there the remnant of the counter-trade is passing west around the magnetic pole. These westerly and north-westerly winds are very light, and like the gentle easterly breeze which sets toward the cumulus clouds and summer showers.

Since most of this work was written, I have procured, and read with great pleasure, Lieutenant Maury’s “Geography of the Sea.” It is a work ofgreat interest, and should be in the hands of every one. The extent of ground covered, however, made it necessary for Lieutenant Maury to introduce much matter not derived from his own investigations. In doing this, he has taken received opinions, and has thereby introduced much heresy. The view he adopts in relation to the monsoons, although the popular one with philosophers, is of that character. He says (page 222):

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