Page:Popular Science Monthly Volume 42.djvu/151

 Rh Each, intended to illustrate some special point, forms a part of a more or less extended series tending toward the elucidation of the earth's structure and history. In the section of Systematic Geography, for instance, the several departments are devoted to the consideration of the materials of the earth's surface; to dynamical and physiographical geology, including the action of various agencies—heat, compression, tension, fracture, air, water, ice, life, etc.; to structural geology, or the architecture of the earth's crust—including stratification and its accompaniments, joints, inclination, strike, dip, igneous effects, and veins; and to stratigraphical or historical geology. The section of Economic Geology is arranged in a similar manner for illustration by specimens of building and ornamental stones, ores, and other useful mineral substances.

Relative Value of Rain and Irrigation.—Chief Fernow remarks, in his report of the Division of Forestry, that the manner in which the water of the atmosphere becomes available—rain—is not the most satisfactory. This because of its irregularity, and on account of its detrimental action in packing the ground and impeding percolation. A large amount of what would be carried off by underground drainage is thus changed into surface-drainage waters. At the same time, by this compacting the soil, capillary action is increased, and evaporation thereby accelerated. Water management, or forest management as a part of it, may be profitably studied in connection with this subject. The forest floor reduces or prevents the injurious mechanical action of the rain, and acts as a regulator of water-flow. Hitherto water management in rainy districts has mainly concerned itself with getting rid of the water as fast as possible, instead of making it do service during its temporary availability by means of proper soil management, horizontal ditches, and reservoirs—drainage and irrigation systems combined. It seems to have been entirely overlooked that irrigation, which has been considered only for arid and subarid regions, can be applied for plant production in well-watered regions with equal benefit and profit, if combined with proper drainage systems and forest management. To pave the way for a better utilization of water-supplies in the Eastern States seems as much a proper function of the Department of Agriculture as the development of irrigation systems in the Western States; and a comprehensive collection of water statistics and forestry statistics with reference to their mutual relation seems to be a desirable task.

The Public School and the University.—The policy adopted several years ago by the University of Michigan, of admitting graduates of the public schools of the State without examination, is represented by the University Record as working well. The faculty feel that, whatever may be the defects of the diploma system, there are gains that more than counterbalance them. The principal gain has been in strengthening the bond between the university and the high schools. Experience goes to show that voluntary initiative of the university and the schools can make good to a great degree the lack of an authoritative State surveillance of public instruction. In many ways the university has been able to exert a salutary influence upon the schools, while its own position before the people of the State has been very greatly strengthened by the system; and this has been done without lowering the standard of scholarship.

Graphite and Lead-pencils.—The ancients were not acquainted with any real drawing lead. The first drawings resembling those made with a pencil appeared in the later middle ages. Silver-pencil drawings by Van Eyck and Memlink are spoken of; the portrait of Petrarch's Laura was made by a contemporary in a similar style; and Michael Angelo sometimes drew with pencils that seem to have been made of a compound of lead and tin. These were exceptions to the general rule. Pens, crayons, and red chalk held the place among artists and in general use now occupied by the pencil. The famous graphite beds of Borrowdale, in Cumberland, were discovered during the reign of Queen Elizabeth in England, and with them the material which was destined to stimulate the rapid development of the pencil industry. Our lead-pencil is really a graphite pencil. The pencils made in England then were quite different from the products of the