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.
In point of fact, it appears from these observations that it resulted from both causes, operating connectedly; and the annals of Science rarely furnish a more striking instance of analogical inference proved true by subsequent investigation.
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 not conform to general results. On the west and north of its curving line, both precipitation and temperature were below the mean.
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.
| LAT. | LON. | JAN. | FEB. | MAR. | APRIL. | MAY. | JUNE. | JULY. | |
| Fort Moultrie | 32.45 | 79.51 | 50.83 | 53.09 | 62.72 | 62.76 | 73.35 | 78.55 | 82.06 |
| Mean of 28 yrs. | 50.36 | 52.41 | 58.68 | 65.44 | 73.42 | 79.01 | 81.72 | ||
| Fort Pierce | 27.30 | 80.20 | 67.91 | 67.33 | 73.01 | 71.10 | 78.41 | 82.09 | 84.16 |
| Mean of 5 yrs. | 62.75 | 64.42 | 69.77 | 73.63 | 76.92 | 79.02 | 82.50 | ||
| Fort Meade | 28.01 | 82.00 | 63.75 | 63.33 | 70.64 | 68.10 | 76.31 | 79.10 | 80.17 |
| Mean of 3 yrs. | 58.40 | 63.23 | 69.02 | 69.89 | 76.69 | 78.24 | 79.76 | ||
| Fort Brooke | 28.00 | 82.28 | 62.94 | 62.36 | 70.06 | 70.07 | 77.49 | 80.51 | 81.08 |
| Mean of 25 yrs. | 61.53 | 63.54 | 67.72 | 71.82 | 76.64 | 79.46 | 80.72 | ||
| Fort Myers | 26.38 | 82.00 | 67.56 | 67.39 | 73.74 | 71.07 | 79.13 | 82.35 | 81.91 |
| Mean of 4 yrs. | 63.39 | 67.98 | 72.19 | 73.86 | 80.13 | 81.25 | 82.87 | ||
| Key West | 24.32 | 81.48 | 71.75 | 71.95 | 76.56 | 73.89 | 80.84 | 83.34 | 83.30 |
| Mean of 14 yrs. | 66.68 | 68.88 | 72.88 | 75.38 | 79.10 | 81.63 | 83.00 | ||
| Fort Barrancas | 30.18 | 87.27 | 54.71 | 54.56 | 64.98 | 62.93 | 75.40 | 81.00 | 84.55 |
| Mean of 17 yrs. | 53.61 | 55.58 | 61.80 | 68.51 | 75.45 | 80.80 | 82.26 | ||
| Mt. Vernon Ars’l | 31.12 | 88.02 | 51.52 | 53.18 | 65.24 | 62.30 | 74.64 | 79.17 | 78.90 |
| Mean of 14 yrs. | 50.44 | 53.69 | 60.26 | 66.87 | 73.92 | 78.03 | 78.62 | ||
| Baton Rouge | 30.26 | 91.18 | 53.43 | 56.48 | 66.24 | 64.63 | 75.10 | 80.61 | 80.09 |
| Mean of 24 yrs. | 53.47 | 55.02 | 61.93 | 69.30 | 75.60 | 80.56 | 81.81 |
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.