Chapter VI (3)

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 they _blow over the desert itself_ on 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 deg. N., and from 10 deg. to 55 deg. 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 deg. TO 5 deg., LONGITUDE FROM GREENWICH 10 deg. TO 55 deg..

+-------------------------------------------------------+
| Course. | July. | August. | Course. | July. | August. |
|-------------------------------------------------------|
| North. | 0 | 0 | S. S. W.| 54 | 111 |
| N. N. E.| 8 | 2 | S. W. | 1 | 29 |
| N. E. | 6 | 2 | W. S. W.| 6 | 19 |
| E. N. E.| 27 | 16 | West. | 2 | 9 |
| East. | 31 | 20 | W. N. W.| 1 | 6 |
| E. S. E.| 120 | 96 | N. W. | 1 | 0 |
| S. E. | 216 | 276 | N. N. W.| 0 | 2 |
| S. S. E.| 218 | 443 | Calm. | 8 | 4 |
| South. | 69 | 279 |---------------------------|
| | | | Total | 768 | 1,314 |
+-------------------------------------------------------+

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

Ascending to the region between 5 deg. and 10 deg. north latitude, and 10 deg. to 55 deg. 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.

+-------------------------------------------------------+
| Course. | July. | August. | Course. | July. | August. |
|-------------------------------------------------------|
| North. | 19 | 6 | S. S. W.| 188 | 368 |
| N. N. E.| 26 | 11 | S. W. | 63 | 94 |
| N. E. | 104 | 32 | W. S. W.| 73 | 93 |
| E. N. E.| 30 | 16 | West. | 33 | 48 |
| East. | 45 | 29 | W. N. W.| 30 | 18 |
| E. S. E.| 36 | 40 | N. W. | 21 | 9 |
| S. E. | 93 | 53 | N. N. W.| 17 | 13 |
| S. S. E.| 225 | 307 | Calm. | 109 | 74 |
| South. | 239 | 514 |---------|-------|---------|
| | | | Total | 1,351 | 1,725 |
+-------------------------------------------------------+

Ascending to the region of 10 deg. to 15 deg. north latitude, and 15 deg. to 45 deg. 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.

+-------------------------------------------------------+
| Course. | July. | August. | Course. | July. | August. |
|-------------------------------------------------------|
| North. | 17 | 55 | S. S. W.| 30 | 71 |
| N. N. E.| 64 | 74 | S. W. | 33 | 63 |
| N. E. | 155 | 149 | W. S. W.| 19 | 43 |
| E. N. E.| 91 | 71 | West. | 12 | 25 |
| East. | 83 | 60 | W. N. W.| 17 | 21 |
| E. S. E.| 25 | 26 | N. W. | 13 | 24 |
| S. E. | 17 | 26 | N. N. W.| 24 | 56 |
| S. S. E.| 13 | 33 | Calm. | 62 | 78 |
| South. | 9 | 44 |---------|-------|---------|
| | | | Total | 684 | 919 |
+-------------------------------------------------------+

Ascending to the region between 15 deg. and 20 deg. north latitude, and 15 deg. to 45 deg. west longitude, we get north of the belt of rains _and 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.

+-------------------------------------------------------+
| Course. | July. | August. | Course. | July. | August. |
|-------------------------------------------------------|
| North. | 39 | 20 | S. S. W.| 0 | 5 |
| N. N. E.| 210 | 185 | S. W. | 0 | 5 |
| N. E. | 112 | 87 | W. S. W.| 8 | 3 |
| E. N. E.| 114 | 104 | West. | 0 | 1 |
| East. | 20 | 36 | W. N. W.| 0 | 4 |
| E. S. E.| 21 | 17 | N. W. | 3 | 4 |
| S. E. | 0 | 2 | N. N. W.| 3 | 31 |
| S. S. E.| 2 | 11 | Calm | 20 | 8 |
| South. | 5 | 1 |---------|-------|---------|
| | | | Total, | 557 | 526 |
+-------------------------------------------------------+

Ascending still further to the region between 20 deg. and 25 deg. north latitude, and 15 deg. and 45 deg. 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; and _only 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.

+-------------------------------------------------------+
| Course. | July. | August. | Course. | July. | August. |
|-------------------------------------------------------|
| North. | 25 | 20 | S. S. W.| 3 | 0 |
| N. N. E.| 210 | 153 | S. W. | 2 | 0 |
| N. E. | 129 | 77 | W. S. W.| 13 | 0 |
| E. N. E.| 110 | 86 | West. | 0 | 0 |
| East. | 8 | 20 | W. N. W.| 0 | 3 |
| E. S. E.| 4 | 11 | N. W. | 2 | 1 |
| S. E. | 0 | 3 | N. N. W.| 5 | 8 |
| S. S. E.| 1 | 7 | Calm. | 2 | 5 |
| South. | 1 | 0 |---------|-------|---------|
| | | | Total, | 515 | 394 |
+-------------------------------------------------------+

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.

+-------------------------------------------------------+
| Course. | July. | August. | Course. | July. | August. |
|-------------------------------------------------------|
| North. | 32 | 19 | S. S. W.| 9 | 6 |
| N. N. E.| 155 | 125 | S. W. | 3 | 9 |
| N. E. | 144 | 35 | W. S. W.| 13 | 14 |
| E. N. E.| 140 | 89 | West. | 12 | 3 |
| East. | 48 | 57 | W. N. W.| 7 | 7 |
| E. S. E.| 31 | 23 | N. W. | 11 | 1 |
| S. E. | 8 | 7 | N. N. W.| 36 | 6 |
| S. S. E.| 8 | 12 | Calm. | 18 | 12 |
| South. | 5 | 4 |---------|-------|---------|
| | | | Total, | 680 | 429 |
+-------------------------------------------------------+

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 deg., 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 the prevalent 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, the _winds 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 of great 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):

"Monsoons are, for the most part, formed of trade-winds. When a
trade-wind is turned back, or diverted, by over-heated districts,
from its regular course at stated seasons of the year, it is regarded
as a monsoon. Thus, the African monsoons of the Atlantic, the
monsoons of the Gulf of Mexico, and the Central American monsoons of
the Pacific, are, for the most part, formed of the north-east
trade-winds, which are turned back to restore the equilibrium which
the over-heated plains of Africa, Utah, Texas, and New Mexico have
disturbed. When the monsoons prevail for five months at a time--for
it takes about a month for them to change and become settled--then
both they and the trade-winds, of which they are formed, are called
monsoons."

Again (Sec. 476-7):

"The agents which produce monsoons reside on the land. These winds
are caused by the rarefaction of the air over large districts of
country situated on the polar edge, or near the polar edge, of the
trade-winds. Thus, the monsoons of the Indian Ocean are caused by the
intense heat which the rays of a cloudless sun produce, during the
summer time, upon the Desert of Cobi and the burning plains of
Central Asia. When the sun is north of the equator, the force of his
rays, beating down upon these wide and thirsty plains, is such as to
cause the vast superincumbent body of air to expand and ascend. There
is, consequently, a rush of air, especially from toward the equator,
to restore the equilibrium; and, in this case, the force which tends
to draw the north-east trade-winds back becomes greater than the
force which is acting to propel them forward. Consequently, they obey
the stronger power, turn back, and become the famous south-west
monsoons of the Indian Ocean, which blow from May to September
inclusive.

"Of course, the vast plains of Asia are not brought up to monsoon
heat _per saltum_, or in a day. They require time both to be heated
up to this point and to be cooled down again. Hence, there is a
conflict for a few weeks about the change of the monsoon, when
neither the trade wind nor the monsoon force has fairly lost or
gained the ascendency. This debatable period amounts to about a month
at each change. So that the monsoons of the Indian Ocean prevail
really for about five months each way, viz.: from May to September,
from the south-west, in obedience to the influence of the over-heated
plains, and from November to March inclusive from the north-east, in
obedience to the trade-wind force."

What the "trade-wind force" is, Lieutenant Maury tells us in another paragraph, viz.: "Calorific action of the sun and diurnal rotation of the earth"--the received calorific theory. I have already shown, I think, conclusively, that there is no expansion and ascent in the supposed region of calms, which induces, or can induce, the trades; and that, in point of fact, the air on the land is cooler under the belt of rains. But as Lieutenant Maury, whose reputation is national, adopts the theory, I shall be pardoned for copying the following table, showing the difference of temperature at two cities of India, before, after, and while the belt of inter-tropical rains is over them. It will be seen that the temperature is actually less when the belt is there, viz., in July and August, than in April and May. _This should be conclusive upon that point._

+----------------------------------------------------+
| | Anjarakandy. | Calcutta. |
| Months. |--------------------|-------------------|
| | Rain. | Temp. | Rain. | Temp. |
|-----------|----------|---------|---------|---------|
| | M. M. | | M. M.| |
| January, | 2,26 | 26 deg.,5 | 0,0 | 18 deg.,4 |
| February, | 2,26 | 27 deg.,7 | 67,68 | 21 deg.,5 |
| March, | 6,77 | 28 deg.,4 | 24,82 | 25 deg.,6 |
| April, | 29,33 | 29 deg.,8 | 130,84 | 28 deg.,5 |
| May, | 175,96 | 28 deg.,6 | 16,24 | 29 deg.,7 |
| June, | 794,05 | 26 deg.,6 | 575,24 | 29 deg.,3 |
| July, | 807,59 | 25 deg.,8 | 338,38 | 28, deg.1 |
| August, | 572,98 | 26 deg.,0 | 311,31 | 28 deg.,3 |
| September,| 311,31 | 26 deg.,4 | 254,91 | 28 deg.,0 |
| October, | 157,91 | 26 deg.,8 | 42,86 | 27 deg.,2 |
| November, | 65,42 | 26 deg.,9 | 20,30 | 23 deg.,0 |
| December, | 29,33 | 26 deg.,5 | 0,0 | 19 deg.,2 |
|-----------|----------|---------|---------|---------|
| Year, | 2955,14 | 27 deg.,2 | 1928,74 | 26 deg.,4 |
+----------------------------------------------------+

Anjarakandy is on the Malabar coast, between 12 deg. and 13 deg. north latitude. Calcutta in an angle of the Bay of Bengal, at 22 deg. 30' north latitude. The former is in and near the focus of the monsoons, and has a temperature in July (when 18 inches of rain fall), about as low as in December.

In the foregoing table from Kaemptz, the rain is in millimetres, about twenty-five of which make an inch, and the temperature is centigrade, which may be raised to Fahrenheit by adding four fifths of the quantity and also 32 deg.--thus, if the height of the centigrade thermometer be 25 deg., add to this four fifths of 25 deg., which is 20 deg., and also 32 deg., the result is 77 deg.. Twenty-five centigrade is therefore equal to seventy-seven Fahrenheit.

Lieutenant Maury is not, and should not be a theorist. He occupies the position, in some sort, of a national _investigator_, and, of course, of national _instructor_. Opinions which emanate from him, or which are endorsed by him, should be accurate. Sooner or later that which he has adopted in relation to the monsoons, and some others, must be abandoned. In addition to what has already been said, I wish to call his, and the reader's attention, to several other facts and considerations in relation to the monsoons, and particularly those of India.

1st. The deserts of Cobi and Bucharia, which constitute the "burning plains" of _Central_ Asia, north-east of the Indian Ocean, lie between 38 deg. and 45 deg. of north latitude, and under the zone of extra-tropical rains. They are not wholly rainless. They partake of that saline character which affects so much of Asia and the western part of this continent. South of them, running nearly east and west, are the lofty ranges of the Himmalaya and Kuenlun Mountains, and the table lands of Thibet. To their saline character, in part, but mainly to the interposition of these mountain ranges, depriving the counter-trade of moisture, they owe their comparative sterility. _If bountifully supplied with rains, this salt would doubtless ere this have been washed to the ocean, as it has been from other countries, once as salt as they._ But they have some rain, and more or less vegetation, and are not intensely hot. They lie too far north, and are too elevated. Their temperature is not materially different from that of the western, and comparatively desert portions of our own country, and they are utterly incapable of creating a monsoon at the Indian Ocean, and especially from the long line of Malabar coast, where the south-west monsoons are found in most strength. The sterile portions of Utah, New Mexico, and Texas are alike incapable of such effect upon the atmosphere of Central America and Mexico. These monsoons commence in May, and prevail until October, and the temperature of the air where they blow ranges with considerable regularity between 76 deg. at night, and 84 deg. at mid-day, on the Malabar coast, and a trifle lower in Central America.

At Fort Fillmore, El Paso, New Mexico, in latitude 32 deg.03, the mean
temperature for

May is 68 deg.
June " 78 deg., 5'
July " 80 deg., 1'
August " 83 deg., 8'
September " 77 deg., 9'
-------
And for the whole period, 77 deg., 1'

At Santa Fe, New Mexico, the mean for
May is 66 deg., 9'
June " 72 deg., 5'
July " 75 deg., 3'
August " 72 deg., 9'
September " 62 deg., 3'
-------
And for the whole period, 69 deg., 3'

Mean of the two united, 73 deg., 2'

The mean of Western Texas is about 2 deg. higher than at Fort Fillmore, and of Utah not materially different; and the mean of _Central_ Asia between 38 deg. and 45 deg. does not materially vary from them.

Now, it is perfectly evident that during May and September the temperature of Central Asia is far below that of the Indian Ocean and India, and never materially exceeds it. Central Asia is hot, "burning," if you please, compared with more elevated, fertile, or better watered territory _in the same latitude_, and so it has been characterized; but not so, compared with the Indian Ocean, or India, where the sun is vertical. During the greater part of the time, therefore, that the monsoons are in full blast, Utah, Texas, and New Mexico, and Cobi, and the burning plains of Asia, are from 5 deg. to 10 deg. colder than the temperature of the place where the monsoons are blowing. Would not such a fact be perfectly conclusive in any other science except theory-swathed meteorology?

2d. The theory assumes that the heated air has an ascensive force, which causes it to rise and create a vacuum, and this vacuum, by its suction, draws in the adjoining air, which immediately ascends. The adjoining air, drawn away from its locality, leaves a vacuum, and that is filled by another rush from the S. W., and so on, till the Indian Ocean is reached, and the monsoons are accounted for.

Now, look at the difficulties:

The highest temperature that can be assumed for the air over Cobi, at any time, without disregarding facts and analogy, is 100 deg.. What is the ascensive power of an area of atmosphere of 100 deg.? For this we have no problem or formula, although problems and formulas abound in the science. Professor Espy relied on heated air only to give the storm a _start_. His main reliance was on the latent heat supposed to be given out during condensation, for his ascensive storm power. But over these "burning plains" there is, according to the theory, no storm or cloud, or condensation on which that supposed reliance for expansion can be placed. What, then, is the ascension force of air at 100 deg.? _We ought to know, for we sometimes have it as high, or within two or three degrees as high, in all the eastern and middle States._

The monsoons blow at from twenty to twenty-five miles an hour, and sometimes more. Is that the ascensive force of air at 100 deg.? At 25 miles an hour it would be 2,200 feet; at 20 miles, 1,760 feet; and at 10 miles, 880 feet per minute.

Does any man believe that either current exists? Why, then, do we not have our hats taken off, or light objects carried up, or have a monsoon, or, at least, have the clouds running up, when we have such elevated temperatures. _Nothing of the kind occurs with us._ Our hottest days are comparatively still days; and I have seen the cumulus sailing gently to the east, horizontally, when the air was at 98 deg.. Why should we be exempt? Is not our air the same and our heat the same?

Again, suppose we grant that the ascensive force is equal to 20 or even 10 miles an hour, will not the adjoining air hold back somewhat to avoid leaving behind an entire vacuum? or, will it all voluntarily rush in, and leave a new complete vacuum? and, if so, why the preference of vacuums by the air, and _when, where, and why_, should the _successive vacuums stop_? Nay, would not gravity fill the second vacuum from _above_, rather than from the south-west side? and will not the air incline to rush in, to some or all these successive vacuums, from some other side than south-west? or, have these deserts the power of selecting the quarter from which their vacuum shall be filled, and of delegating it to succeeding vacuums? Would it not incline to rush in from the east and west where there are no elevations, rather than from the S. W. and over the Kuenlun Mountains, the intervening ridges and valleys of Thibet, the lofty Himmalayas, the extent of India, and the Ghaut Mountains, from three to four thousand feet high, on its eastern coast? Would it not, at least, _leak in a little_, and lessen the force with which the vacuums would draw from the far-off Indian Ocean, so that the monsoon could not blow with equal force? or, if Cobi and its fellow deserts _must_ and _can_ draw from an _ocean_, why not from the head of the Arabian Sea, or Bay of Bengal, or the China Sea, which are nearer, or from the Japan Sea, which is still nearer, or the Yellow Sea, which is close by? Why draw only from under the central belt of rains? Nay, what shall be done with Professor Dove? In a recent article, republished in the American Journal of Science and Art, for January, 1855, he says: "A greatly diminished atmospheric pressure taking place in summer over the _whole continent_ of Asia must produce an influx from all surrounding parts; and thus we have west winds in Europe, north winds in the Icy Sea, east winds on the east coast of Asia, and south winds in India. _The monsoon itself becomes, as we see, in this point of view, only a secondary phenomena._" This looks very like _antagonism_. Who shall we believe?

Again, suppose you get one atmosphere from the whole area, raised up by the supposed ascensive force, and at the rate of twenty-five, twenty, or even ten miles an hour, and a new volume drawn in from the south-west, and _over the mountains_: will it not take a _little time_ for _that_ to _heat up_? Does it heat so fast as to _keep up the ascensive force_ without intermission, at twenty-five, or twenty, or ten miles the hour? What says Mr. Ericsson to this? Can he not arrange with a moderate lens, to move his engine with the rays of the summer sun? Nay, Lieutenant Maury says they can not heat up "_per saltum_, or in a day." But according to a reasonable calculation, they must heat up the air from 80 deg., or less, to 100 deg., at the rate of 2,000 feet per minute. Heating 2,000 feet in depth, in the proportion of 20 deg. per minute, night and day, for five months, is "_per saltum_" in a minute, and 1,440 "_saltums_" per day!

And further still, the Indian Ocean, from which the monsoons are drawn to Cobi and Central Asia to the N. E., is during those months covered by the belt of calms and rains, as heretofore stated; and the S. E. trades blowing into it are attributed to the suction created by the ascent of heated air _there_. So, then, the monsoons are blowing away from under the rainy belt, from 500 to 1000 miles, to Cobi and the burning plains of Asia, while the ascensive force of that belt is such as to draw the S. E. trades toward the very spot, a distance of 1,200 or 1,500 miles, at 20 miles an hour! What must the ascensive force over Cobi, etc., be, if, as a "stronger power," it can overcome an ascensive force over the Indian Ocean sufficient to draw the S. E. trades 1,500 miles, at 20 miles an hour; and, in addition to the force necessary to resist this central suction, not only stop or hold back the N. E. trade, but reverse it and draw it back, at 20 miles an hour, as a monsoon? Must it not be, at least, double that of the belt of calms, or the "great region of expansion," as Professor Dove calls it?

Now, I am irresistibly tempted to ask whether a meteorological theory can be too absurd for credence, and whether it would not be as well to endow the deserts with ribs and lungs, and a proboscis long enough to reach the Indian Ocean, and the necessary power of inspiration and expiration? Such a theory would avoid all difficulties, conflict with no more analogies, and, in my judgment, be as much entitled to credit as the one to which meteorologists adhere.

3d. North of the Malabar coast, in the north-west of India, lies an extensive desert. West of that is Beloochistan, with its rainless deserts. Further west are the rainless deserts of Arabia, and these three, including the Persian deserts further north, cover _as much surface_ as the deserts of Cobi and Bucharia--have the sun vertical in part, and nearly so over the entire surface--_are more intensely hot_, and lie within _one third of the distance_ which intervenes between that desert and the Indian Ocean off the Malabar coast, with _an open sea and_ no _mountains between_. Now, look at it. The north-west desert of India, and the rainless deserts of Beloochistan and Arabia _reverse no trade_ and _have no monsoon_, although the Arabian Sea heads right up among them. They do not attract one from the Indian Ocean off the Malabar coast, although not more than one third of the distance off, and without such mountains and table lands intervening as separate that coast from Cobi. It is said by Lieutenant Maury that the monsoons, "_obey the stronger force_." But which is the stronger force? Cobi, not _wholly_ rainless, lying north of 35 deg., under the zone of extra-tropical rains, with India and the Ghauts, the Himmalaya Mountains, the table lands of Thibet, and the Kuenlun Mountains between? or the deserts of India, Beloochistan, and Arabia, _wholly rainless_, and _intensely hot, near by_, and in _open view_. There can be but one answer to this question. Nothing in the way of desert barrenness, or elevated temperature, unless it be those of Sahara, can exceed the deserts about the head of the Arabian Sea and Persian Gulf. Certainly those of Cobi can not compare with them; yet the trades blow steadily over them, although more northerly there, as every where, near their northern limits, especially on land. Says Hopkins, in his atmospheric changes:

"If any one part of the broad expanse of the continent of Asia could
be heated so as to draw air from the Arabian Sea and the Indian Ocean
during the summer, it would be that part which lies between
Hindoostan and the Lake of Aral, including the region between the
Valley of the Oxus and Persia, and the land of this part, unlike
Hindoostan, is not screened from the sun by thick vapors. But what
says Burnes respecting the winds of this part? Why, that about the
latter end of June, though the thermometer was at 103 deg. in the day,
'In this country a steady wind generally blows from the north.' And
on the 23d of August, after having passed the Oxus--'The heat of the
sand rose to 150 deg., and that of the atmosphere exceeded 100 deg., but the
wind blew steadily, nor do I believe that it would be possible to
traverse this tract in summer if it ceased to blow. The steady manner
in which it comes from one direction is remarkable in this inland
country.' Again--'The air itself was not disturbed but by the usual
north wind that blows steadily in this desert.' And he has many other
similar passages."

Here there is a vast tract of country south of 35 deg. which has a temperature often of 103 deg., and does not reverse the trade and create a monsoon. How utterly unphilosophical, then, to attribute the monsoons to Cobi because they "obey the stronger force!" or to attribute them to it at all.

4th. The monsoons can not be _traced from_ the Malabar coast _to Cobi_. They do not exist on the south-west of Cobi and near it, where they should in greatest force, and there is no connection, in fact, shown between them. They do not often extend more than twenty-five miles inland, or to the east of the Ghauts. There are no corresponding intervening monsoons crossing India to the mountains--none over the mountains and table lands--none under the northern lee of the mountains--nor, in short, on the whole track, nor any S. W. winds except such as naturally belong to the action of the curving counter-trade.

Finally, the investigations of Commodore Wilkes on Mauna Loa, a mountain upon Hawaii, more than 13,000 feet high, and the observations of Professor Wise and other aeronauts are sufficient to put this whole matter of heated lands and ascent of the atmosphere as the cause of winds, at rest. Commodore Wilkes was encamped for about _twenty days_ on Pendulum Peak, in December and January 1840. Although not up to the elevation of the counter-trade in that latitude, he was above the local clouds which form over the island during the day, where the sea breezes blow in with as great strength as any where. Indeed, he was on the top of the "lofty conical mountain" to which Caleb Williams alludes in the letter to Professor Espy I have quoted, and above the spot where Professor Espy assumed that the clouds were rising with such force as to induce the strong sea breezes of that island. During this time there were two snow-storms on Mauna Loa, and they had the wind from the S. W. during the storm, as might be expected, looking at the situation of the mountain on the western side of the island. These storms moved to the N. W., and were observed at the other islands in that direction as rain.

The local clouds lay over the island every day, as they do over active volcanic islands which are very elevated, although it was the dry season. _Nothing like an ascent of the clouds or of the currents of air from the ocean was observed._ On the contrary, the clouds formed before the sea breezes set in, and the latter blew from the different sides of the island in under the clouds, and outward again, probably on the opposite side. The whole interior of the island is elevated, and its temperature low; and _there was no elevation of temperature on the high portions of the island over which the clouds formed, and toward which the winds blew, which could create an upward current_.

"During our stay on the summit, we took much pleasure and interest in
watching the various movements of the clouds; this day in particular,
they attracted our attention; the whole island beneath us was
covered with a dense white mass, in the center of which was the cloud
of the volcano rising like an immense dome. All was motionless until
the hour arrived when the sea-breeze set in from the different sides
of the island; a motion was then seen in the clouds, at the opposite
extremities, both of which seemed apparently moving toward the same
center, in undulations, until they became quite compact, and so
contracted in space as to enable us to see a well defined horizon; at
the same time there was a wind from the mountain, at right angles,
that was affecting the mass, and drawing it asunder in the opposite
direction. The play of these masses was at times in circular orbits,
as they became influenced alternately by the different forces, until
the whole was passing to and from the center in every direction,
assuming every variety of form, shape and motion.

"On other days clouds would approach us from the S. W. when we had a
strong N. E. trade-wind blowing, coming up with cumulus front,
reaching the height of about eight thousand feet, spreading
horizontally, and then dissipating. At times they would be seen lying
over the island in large horizontal sheets as white as the purest
snow, with a sky above of the deepest azure blue that fancy can
depict. I saw nothing in it approaching to blackness at any time."
(Exploring Expedition, vol iv. p. 155).

Here, in the last paragraph, we have the whole truth disclosed. The N. E. trade was blowing on Mauna Loa, 13,000 feet above the sea, and the sea-breeze blew in on the _leeward side_, its moisture condensing over the volcanic island, but without rising _up the mountain_, or _through the surface-trade_, or _above 8,000 feet_.

So, too, the celebrated aeronaut, Mr. Wise, in the course of more than a hundred ascensions, some during high wind, and others during rain storms, never met with an ascending current, except in a single instance, in the body of a hail-cloud, and then there were descending currents also, the usual intestine motion of hail-cloud with its opposite polarities.

I copy a description of his passage through the clouds of a rain-storm, and his floating a long period above them; and there was no ascending current which disturbed their horizontal repose or progression. The double layer is not uncommon--condensation taking place at the connection of the upper and lower portions of the trades, with the surrounding atmosphere; or in the trade, and by _induction in the surface atmosphere_ at the same time. Such instances are frequently visible, and if his ascensions had been undertaken at other times in stormy weather he would have seen more of them.

"Before I passed the limits of the borough, a parachute, containing
an animal, was dropped, which descended fast and steady, and, just as
it reached the earth, my aerial ship entered a dense black body of
clouds. Ten minutes were consumed in penetrating this dismal ocean of
rainy vapor, occasionally meeting with great chasms, ravines, and
defiles, of different shades of light and darkness. When I emerged
from this ocean of clouds, a new and wonderfully magnificent scene
greeted my eyes. A faint sunshine shed its warmth and luster over the
surface of this vast cloud sea. The balloon rose more rapidly after
it got above it. Viewing it from an elevation above the surface, I
discovered it to present the same shape of the earth beneath,
developing mountains and valleys, corresponding to those on the
earth's surface. The profile of the cloud-surface was more depressed
than that on the earth, and, in the distance of the cloud-valley a
magnificent sight presented itself. Pyramids and castles, rocks and
reefs, icebergs and ships, towers and domes--every thing belonging to
the grand and magnificent could be seen in this distant harbor; the
half-obscured sun shedding his mellow light upon it, gave it a rich
and dazzling luster. They were really "castles in the air," formed of
the clouds. Casting my eyes upward, I was astonished in beholding
another cloud-stratum, far above the lower one; it was what is
commonly termed a "mackerel sky," the sun faintly shining through it.
The balloon seemed to be stationary; the clouds above and below
appeared to be quiescent; the air castles, in the distance, stood to
their places; silence reigned supreme; it was solemnly sublime.
Solitary and alone in a mansion of the skies, my very soul swelled
with emotion; I had no companion to pour out my feelings to. Great
God, what a scene of grandeur! Such were my thoughts; a reverence for
the works of nature, an admiration indescribable. The solemn
grandeur--the very stillness that surrounded me--seemed to make a
sound of praise.

"This was a scene such that I never beheld one before or after
exactly like it. Two perfect layers of clouds, one not a mile above
the earth; the other, about a mile higher; and, between the two, a
clear atmosphere, in the midst of which the balloon stood quietly in
space. It was, indeed, a strange sight--a meteorological fact, which
we cannot possibly see or make ourselves acquainted with, without
soaring above the surface of the earth." (History and Practice of
Aeronautics, p. 209).

This is graphic. Perhaps in relation to the conformity of the upper surface of the inferior layer of clouds, to the irregularities of the earth's surface, he was misled during the enthusiasm of the moment. He is certainly mistaken as to the possibility of observing these double layers from the earth; I have seen them in hundreds of instances. But in relation to the _quiescence_ of the clouds for an hour, and _the entire absence of ascending currents_, he could not be mistaken.

And now, in the absence of all direct proof to sustain the hypothesis, that the heating of the land produces ascending currents, and thereby the winds, and especially the monsoons, and in view of all the adverse evidence, I put it to Lieutenant Maury, and every sincere searcher after meteorological truth, whether the theory should not be abandoned.