Daniel Draper

“ As regards percolation, much depends on the rate at which the rain falls, and the contemporaneous condition of the surface of the ground. The supply may come so rapidly that there is not time for it to soak into the earth. In this manner the quantity that properly belongs to a whole month may fall in the course of a few hours, and, rushing over the surface, may be lost. Again, if the surface be frozen, it may be impossible for the water to percolate into the ground, and, though it may descend in a more moderate manner, it may, in this as in the preceding case, be lost. ”

“ There is a general impression that this alleged deficiency was to such an amount as to endanger a due supply to New York for the current year. And not only this, it has also been asserted that for several years past there has been a steadily occurring diminution in the rainfall. While the quantity of water has thus been becoming less and less, the demand has been becoming greater. Not only has the population of the city increased, but also that of the suburban districts, which derive their supplies from the same water gathering grounds that we do. ”

“ The actual supply of water does not depend on rainfall alone. It is diminished by evaporation and also by percolation. When the condition of the atmosphere is such that, either by reason of the heat, the prevalence of dry winds, and other such causes, the water that has fallen is exposed to rapid vaporization, the available supply necessarily becomes less. ”

“ Thus, again, we reach the same conclusion in the case of the city of Charleston that we arrived at in the case of New York, Philadelphia, and Boston, that the winter climate has not undergone any change.
The general conclusion which this examination seems to warrant, both as regards rainfall and winter climate, is this, that there has been no change in the lapse of many years. None can be substantiated as having occurred within a century. ”

“ Moreover, on sunshiny days, the reflection and radiation of the sun's warmth from the vertical sides of the houses must tend in no inconsiderable degree to raise the temperature locally, and aid in producing a thaw. The facts observed in a city are hence not a complete guide in the discussion of general climate changes. ”

“ Land that has been ploughed and exposes a dark surface to the sun, absorbs more heat, that is, becomes hotter, than land covered with forest-growth. It does not seem unreasonable, then, to suppose that, where thousands of square miles of surface have been submitted to such operations, the corresponding effect should be traceable, at least in the temperature of certain seasons of the year. ”

“ A sunflower will thus remove twenty ounces of water in a single day. There is in this respect a waste which varies in the different months, being greatest in those during which general vegetation is most rapid, and less in those—the winter months—when it is torpid. ”

“ It may, however, be supposed, that conclusions which apply to the old settled countries of Europe, in which but few important topographical changes through agricultural or other operations have taken place for many years, will scarcely apply to America, wherein the clearing of land and agricultural surface changes have been occurring on a very extensive scale. ”

“ It is the belief of European meteorologists that the mean rainfall on the western portions of that continent varies little, if at all, when periods of many years are considered. In England there are rainfall records reaching back to 1677. Since 1725 these records are unbroken; at present there are more than 1,500 rain-gauge stations in that country. The Scotch observations extend to 1731, the Irish to 1791. ”