  Since this work was completed I have received a very valuable publication, entitled, the “Army Meteorological Register.” It is a compilation of the observations made by the officers of the medical department of the army, at the military Posts of the United States, from 1843 to 1854 inclusive, prepared under the supervision of the Surgeon-general, and published by direction of the Secretary of War. To this, there is appended a report or general review of the prominent features of American climatology, so far as the basis afforded by the published observation of the army medical Bureau would warrant positive deduction, by Mr. Lorin Blodget, a distinguished meteorologist, accompanied by temperature and rain charts, for each of the four seasons;—exhibiting the various local differences and peculiarities relative to temperature and precipitation in each. These local differences and peculiarities and contrasts are deduced and delineated by Mr. Blodget with much ability. He was fettered, however, by the prevailing calorific theories, and the unfortunate practice of grouping the phenomena into means for the seasons, Spring, Summer, Autumn, and Winter, which grouping is arbitrary, and comparatively uninstructive. Hence, he failed to discover what the tables and summaries most clearly disclose—the principles and system unfolded in the foregoing work. But the summaries of this register contain observations made at posts in Western and Southwestern Texas, in Kansas and Nebraska, and in New Mexico and California, where there has been a dearth of such observations hitherto, and enable me to demonstrate, more conclusively, and I think so that none can fail to understand it, the truth of the philosophy I have endeavored to exhibit. To do this, I will take a year,—divide it into two seasons, the periods of northern and southern transit, the only natural and correct division—and note the phenomena in each, as each progresses. And I will take the year 1854, because that is the last year for which the record of observation is complete; because it had marked peculiarities which are remembered; and because I have alluded to those peculiarities, and those allusions should be confirmed or disproved by the record. Unless I mistake exceedingly, the confirmation will be found signal and convincing. I have assumed, pp. 187, 351, that the transits were greater in some seasons than others; that the drought of 1854 was owing to an extreme northern transit, or to an extension west of the concentrated counter-trade, or both, leaving us less supplied with moisture than usual. Commencing then with the commencement of the northern transit about the 1st of February, we are enabled to trace the then location of our concentrated trade, and its subsequent progress to the north till August, and its influence upon temperature and precipitation. And we can also trace the situation during the same period, of the intervening drought, and the inter-tropical belt of rains, and the extension of the latter north over Florida and the cotton-planting States. On the 1st of February, 1854, our counter-trade was somewhat more concentrated on its extreme winter curve, over the Southern States, than usual. Its line of excess reached up from Fort Brooke, on the peninsula of Florida, to the northwest, a little east of Pensacola on the gulf, cutting Mount Vernon Arsenal north of Pensacola, and extending thence north-westwardly on to Eastern Louisiana, and curving thence and passing N. E. or E. N. E., to the Atlantic, about the waters of the Chesapeake Bay. It thinned out to the west over New Orleans and Baton Rouge, supplying them moderately, but did not extend to the forts of Texas on the west, nor the posts in the Indian Territory at the N. W. It was east of Fort Towson, which is the south-eastern one. It did not reach St. Louis on the north, nor extend north of the Ohio River, as will appear from the tables hereinafter given. The following cut shows substantially its situation on the 1st of February. Now, during the month of January, we find the following state of things. Under this concentrated trade, the temperature was above the mean, even if Forts Monroe and McHenry on the Atlantic are included; but Mr. Blodget discredits their returns, and some others which do Under the counter trade, we have the following stations, with their actual and mean temperature. I have inserted the temperature for several subsequent months, to show a depression in April. TABLE I.
It will be seen that the temperature was above the mean in January at every post except Baton Rouge, and there it was at the mean. We shall see hereafter that Baton Rouge was near its western line. Under this trade during this month, and at the same posts, the fall of rain was as follows, compared with the mean:— TABLE II.
It will be observed that in February the counter-trade and extra-tropical belt had moved up from Key West, and a drought, which sometimes intervenes between the concentrated counter-trade and the In March, the intervening drought appeared at the other posts on the peninsula, and also at Fort Moultrie, followed much more closely than usual, by the inter-tropical belt of rains. In April, the drought appeared at Fort Barrancas and Mount Vernon Arsenal (the wave of precipitation having moved to the west), and slightly in comparison at Baton Rouge. If now we look at the condition of things, west and north of the curving line of concentrated trade, from Fort Brown, at the mouth of the Rio Grande, in South-western Texas, through that State, the Indian Territory, Arkansas, Missouri, Kentucky, and Northern Pennsylvania, to the Atlantic, we find the thermometer every where in January below the mean. The following table will show this, and the precipitation for that month and February:— TABLE III.
The situation of the belt which supplied the western coast in winter, and its excess of precipitation, are also represented upon the cut. The intervening area was not without counter-trade and precipitation—the latter, of course, greatest over the area of intensity—but they were comparatively less, as the tables will show. The following cut and table show the situation of the concentrated counter-trade in March. TABLE IV.
In April, we find it had progressed rapidly west and north-west, and its position is shown by the following cut and table. TABLE V.
We see, too, that both east and west of the mountains, its focus of precipitation was one month in advance of the mean. At all the The observations for April disclose another singular and instructive condition. The temperature, that had every where been above the mean in March, fell below it in April under the concentrated trade. And snow fell on three days in some localities, and four in others. Along the Ohio River, it fell to the depth of 8 to 10 inches on the 17th, and east of the mountains to a greater depth on the 18th, one day later. It fell to the depth of 4 inches at Marietta on the 29th also. Dr. Hilldreth, American Journal of Science for March, 1855, says:— “It is a singular fact that the deepest snow, 8 inches, fell on the 17th of April, and at the head waters about Pittsburg over a foot. Also, on the 29th of the month, at Marietta, 4 inches, a very rare occurrence.” This depression of the temperature was quite general, but the fall of snow was local. The latter was north of a line drawn from Fort Laramie, at the base of the Rocky Mountains, in an E. S. E. direction—north of Forts Kearney and Leavenworth, and of St. Louis, but south of Newport barracks in Kentucky, and from thence to the Atlantic. Snow fell at every station north of this line, at no station south of it. The depression of temperature, however, was experienced over the continent, east of the Rocky Mountains, under, and south of, the belt of precipitation. Now what occasioned this general depression of temperature, and local fall of snow? It will not do to say, as perhaps some calorific theorist may be inclined to say, because the concentrated trade had been carried up where it was cold, a month too soon; or that the sun had heated the land in advance of it, and drawn it up. For, 1st, it might be asked how, if it was warm enough to draw it up, could it be cold enough to make it snow; or, 2d, how happened it to start, when, as we have seen, it was warmer than the mean under it, and colder than the mean to the north and west of it, when it commenced its journey? But again, it snowed at posts north of the line, while the thermometer remained above the mean; and the thermometer fell below the mean down to Fort Brown in south-western Texas, and at Key West in the southern part of Florida; and what is more remarkable still, at Key West, Fort Barrancas, and every other south-eastern station, except Forts Brooke and Moultrie, it not only fell below the mean of the month, but below the actual temperature of March. (See Table I.) At Forts Brooke and Moultrie it did not rise above that temperature. West of the Rocky Mountains the depression was not felt; nor at stations north, or north-west of the belt of precipitation. It is obvious, the calorific theory can furnish no rational explanation of this matter; for the reason that, whatever the cause, it operated In May and June, the trade became more concentrated, a perfectly developed belt from the Rio Grande to the Lakes and British possessions, and doubtless to the Atlantic, with every where a central focus of excessive precipitation, gathering to itself in one vast wave the current that should have been spread out over the whole country; and leaving every where on its eastern and southern borders, down to the northern edge of the inter-tropical belt of rains—(which extended up to lines drawn from Baton Rouge to Charleston)—a perfectly well developed and defined drought. That drought will long be remembered. The following cuts show, approximately, the location of the belt of precipitation and drought for those months, and the table which follows will show their correctness. The tables also show that this wave was occasionally a double, or divided one—evinced by an intervening partial precipitation. Tables IV., V., and VI., also show the commencement of the drought at the several stations, as the wave moved to the west and north. MAY. TABLE VI.
TABLE VII. Situation of the focus of Precipitation in July and August.
I have not space for all the comment which this exposition is calculated to induce. The reader will not only find in it an explanation of the extraordinary character of the summer of 1854, but will see from the means, that it was but an excessive development of an Annual Phenomenon,—the Progress of a Concentrated Counter-trade. It is not necessary to follow with particularity the return transit. Its return progress was slow, and it was every where behind time. The autumn was warm, and so, indeed, were December and January, west of the area of magnetic intensity, although upon, and east of it, there was a depression in December. The retreating but lingering edge of counter-trade, with its excess of snow for the season, caught the Iron Horse, with its train and passengers, upon the prairies of the west, and laid its embargoing hands upon them. Few, if any, can have forgotten the thrilling accounts which reached us from that section, of the sufferings endured by those who were thus embargoed for days and nights, far from the comfortable habitations of their fellow men. But the return transit, though slow, was extreme, and February and March were exceedingly cold for the season. The transit to the north, again, did not commence as early as usual, and the spring was backward, and the summer cool. Both were without irregularity, and the season was productive. The following table exhibits the temperature on a line of posts, running north and south at the west, during the winter months of 1855, and will illustrate what has been said. TABLE VIII.
The return transit to the south for this winter, 1855-6, has been an extreme one. It is too early yet (Feb. 18th) to write its history, but the extreme southern transit is as obvious as the unusual severity of the cold. The rains which usually fall upon the Southern States There is a mass of other evidence in these summaries which shows the truth of what I have written. There is not a deduction of Mr. Blodget which it will not explain. The ascent of the summer lines of temperature to the west is explained by the diminution of magnetic intensity. Their descent in winter by the location and attractions of the concentrated trade. The excess of precipitation in Alabama and Mississippi by the succession of summer and winter belts. That of the interior of the Atlantic slope in summer, by the showers which fall upon the elevations; and of the coast, by the easterly storms and their attraction of the surface atmosphere of the ocean, at other seasons. But I cannot further particularize. Even the influence of the spots is clearly demonstrated by the observations at interior stations, which were unaffected by contiguous oceans or elevations. At Forts Washita, Gibson, Scott, Smith, and others, the years 1847 and 1848 were below the mean. All that evidence, and those deductions, however, I must pass by for want of space, and take leave of the subject. Footnotes: [1] See the diagram for summer at page 55. [2] Law of Storms, p. 42. [3] Kearakakua Bay (called Cavrico above), is on the S. W. side of the island, and the trade was reversed during the day by the cloud condensation inland. [4] Lieutenant Wilkes spent twenty days upon the top of this or an adjoining mountain, and his observations there will be alluded to in another connection. [5] All attempts to produce this result by the sudden exhaustion of air about the chickens in receivers, or shooting them from cannons, have failed, and no patent for a chicken-picker has been applied for. [6] A meter is 1 yard, and .0936 of a yard. [7] See his map, accompanying the Geography of the Sea. [8] See Am. Jour. of Science, New Series, Vol. 18. p. 187. [9] Their estimate was 100 to 120 miles. [10] Since the text was in type, and, as might have been anticipated, we have intelligence confirmatory of this, from the Cape De Verde Islands. The inter-tropical belt of rains has not moved as far north as the northern islands—they have had no rain—and the people are in a starving condition. Transcriber’s Notes: Punctuation has been corrected without note. Other than the corrections noted by hover information, inconsistencies in spelling and hyphenation have been retained from the original. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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