Page:Popular Science Monthly Volume 22.djvu/797

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quickest way possible to clear a space in which to cultivate his wheat and corn, and pasture his herds, or from the fire lighted recklessly or by accident by some passing huntsman or traveler.

In showing the relative position of our forests in respect to land elevation and the vicinity of streams, the census report will show the relation of the forests to the water-supply, and consequently their influence upon agriculture and manufactures. It will indicate their influence upon rain-fall and climate, as well as upon the course and effect of winds, whether considered in their mechanical or their meteorological relations. It will have an important use also as indicating the relative healthfulness of different portions of our wide and diversified domain.

In prosecuting his study of our forests, Professor Sargent has gathered a large collection of specimens of the different woods. These will show the natural appearance of the trees, and the variation of appearance and texture caused by growth under differing circumstances of soil and climate. From these specimens portions have also been taken and carefully worked down so as to show the grain and the susceptibility to polish, and their consequent value for mechanical and artistic purposes. The beauty of our native woods, and their adaptation on this account to the manufacture of cabinet-work, and to the interior finish of dwellings, will be made to appear as never before, and will be a surprise to many. It will be seen that we have gone abroad and procured materials for cabinet and carpentry uses at great expense when our own forests stood ready to supply all that the most fastidious taste could require. Professor Brewer, of Yale College, reports that there are probably 800 species of woody plants indigenous to the United States, of which 250 attain a height of thirty feet, and are abundant in some portion of the country.

Careful experiments have also been made in order to determine the relative value of our woods for the purposes of construction and for use as fuel. Blocks and sections of a great variety of trees have been selected, reduced to the same dimensions, freed to an equal extent from moisture—in other words, brought, so far as possible, to the same conditions—and then subjected to treatment at the United States Arsenal at Watertown, by means of nice and powerful machinery, in the hands of careful manipulators, for the purpose of determining the respective amounts of resistance to a crushing and a fracturing strain. Similar pieces have also been burned, under like circumstances, as nearly as possible, and the amount of heat developed by their combustion accurately determined. The relative value as fuel of the different kinds of wood with which our country abounds has thus been ascertained. Probably no more trustworthy and decisive experiments have ever been made for the purpose of showing the value of different woods for the uses of construction or as sources of heat.

One of the peculiar and, practically, most valuable features of the