Page:Popular Science Monthly Volume 27.djvu/538

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THE POPULAR SCIENCE MONTHLY.

knowledge of every man, and therefore such as may most fitly be set forth in a publication outside of that field of special and technical record which is devoted to professional observation and experience.—Nineteenth Century.


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BUILDING AND ORNAMENTAL STONES OF THE UNITED STATES.

By GEORGE P. MERRILL.

WHEN, early in his curatorship in the National Museum, Dr. George W. Hawes, one of the leading American lithologists, assumed charge of that branch of the tenth census relating to the quarrying industry of the United States, it is doubtful if any but himself fully realized the importance of the undertaking aside from its statistical bearings. Dr. Hawes was, however, not a man to be satisfied with figures alone, or one who considered the scope of a census to be merely the compilation of statistics, and in selecting his assistants he did so with especial reference to their qualifications in other lines of work as well. Thus we find upon his list the names of such geologists as Professors Shaler and Wolff, of Harvard; Hitchcock, of Dartmouth; Winchell, of Minneapolis; and others of equal note and ability. These assistants, or special agents as they were called, visited each quarry in person within their respective districts, and, together with collecting the necessary information relative to the amount, kind, and value of stone quarried, number of men employed, etc., made all possible observations in regard to the geological age of the stone, its disposition in the quarry, weathering qualities as displayed in those portions of the outcrop that had been exposed for ages to the action of atmospheric agencies, and, lastly, selected samples of the rock in the form of blocks of sufficient size to dress into four-inch cubes and forwarded them by mail to the National Museum, at Washington, for further examination.[1] Here a corps of assistants was employed who selected samples for chemical and microscopic analysis, and left the block to be handsomely dressed into a four-inch cube and placed permanently upon exhibition, having mean-while made careful notes upon its working qualities. Small chips of each rock were ground into films so thin as to be perfectly transparent, and submitted to microscopic examination in order not only to determine what the rock was, but also to ascertain if it contained any mineral constituents liable to unfavorable change on exposure to the weather. Whenever necessary, chemical analysis was resorted to to further aid in the solution of the problems involved.

  1. These blocks weighed from six to ten pounds each, but, being Government matter, were allowed to pass through the mails, though greatly exceeding in weight the limit set by law.