Although a much greater quantity of rain falls in mountainous districts (within certain limits of elevation) than in the plains, yet a greater quantity of rain falls at the surface of the ground than at an elevation of a few hundred feet. Thus, from experiments which were carefully made at York, it was ascertained that there fell eight and a half inches more rain at the surface of the ground, in the course of twelve months, than at the top of the Minster, which is 212 feet high. Similar results have been obtained in many other places.
Some observations upon this point may also be found in the Report of the Smithsonian Institution for 1855, at p. 210, given by Professor C. W. Morris, of New York.
Again, the evaporation from the surface of water being much greater than from the land, clouds that are wafted by the winds from the sea to the land, condense their vapor upon the colder hills and mountain sides, and yield rain, so that high lands near the sea or other large bodies of water, from which the winds generally blow, have a greater proportion of rainy days and a greater fall of rain than lands more remote from water. The annual rain-fall in the lake districts in Cumberland County, in England, sometimes amounts to more than 150 inches.
With a desire to contribute as much as possible to the stock of accurate knowledge on this subject, we availed ourselves of the kindly offered services of our friends, Shedd and Edson, in preparing a carefully considered article upon a part of our general subject, which has much engaged their attention. Neither the article itself, nor the observations of Dr. Hobbs, which form a part of its basis, has ever before been published, and we believe our pages cannot be better occupied than by giving them in the language of our friends:
"All vegetables, in the various stages of growth, require warmth, air, and moisture, to support life and health.
Below the surface of the ground there is a body of stagnant water, sometimes at a great depth, but in retentive soils usually within a foot or two of the surface. This stagnant water not only excludes the air, but renders the soil much colder, and, being in itself of no benefit, without warmth and air, its removal to a greater depth is very desirable.
A knowledge of the depth to which this water-table should be removed, and of the means of removing it, constitutes the science of draining, and in its discussion, a knowledge of the rain-fall, humidity of the atmosphere, and amount of evaporation, is very important.
The amount of rain-fall, as shown by the hyetal, or rain-chart, of North America, by Lorin Blodget, is thirty inches vertical depth in the basin of the great lakes; thirty-two inches on Lake Erie and Lake Champlain; thirty-six inches in the valley of the Hudson, on the head waters of the Ohio, through the middle portions of Pennsylvania and Virginia, and western portion of North Carolina; forty inches in the extreme eastern and the northern portion of Maine, northern portions of New Hampshire and Vermont, south-eastern counties of Massachusetts, Central New York, north-east portion of Pennsylvania, south-east portion of New Jersey and Delaware; also, on a narrow belt running down from the western portion of Maryland, through Virginia and North Carolina, to the north-western portion of South Carolina; thence, up through the western portion of Virginia, north-east portion of Ohio, Northern Indiana and Illinois, to Prairie du Chien; forty-two inches on the east coast of Maine, Eastern Massachusetts, Rhode Island, and Connecticut, and middle portion of Maryland; thence, on a narrow belt to South Carolina; thence, up through Eastern Tennessee, through Central Ohio, Indiana, and Illinois, to Iowa; thence, down through Western Missouri and Texas to the Gulf of Mexico; forty-five inches from Concord, New Hampshire, through Worcester, Mass., Western Connecticut, and the City of New York, to the Susquehanna River, just north of Maryland; also, at Richmond, Va., Raleigh, N. C., Augusta, Geo., Knoxville, Tenn., Indianopolis, Ind., Springfield, Ill., St. Louis, Mo.; thence, through Western Arkansas, across Red River to the Gulf of Mexico. From the belt just described, the rain-fall increases inland and southward, until at Mobile, Ala., the rain-fall is sixty-three inches. The same amount also falls in the extreme southern portion of Florida.
In England, the average rain-fall in the eastern portion is represented at twenty inches; in the middle portion, twenty-two inches; in the southern and western, thirty inches; in the extreme south-western, forty-five inches; and in Wales, fifty inches. In the eastern portion of Ireland, it is twenty-five inches; and in the western, forty inches.
Observations at London for forty years, by Dalton, gave average fall of 20.69 inches. Observations at New Bedford, Mass., for forty-three years, by S. Rodman, gave average fall of 41.03 inches—about double the amount in London. The mean quantity for each month, at both places, is as follows: