Page:Popular Science Monthly Volume 48.djvu/315

Rh the time muzzled, but in many instances with growl barely suppressed. In a rough-and-ready way one may estimate the cost of this fleet of one hundred great armor-clad ships of war, with twenty-five lesser vessels, at approximately $200,000,000, which is probably four or five times the cost of the peaceful water-way, the opening of which they were called together to celebrate. The United States was represented by one battle ship and, I believe, by one of our two 'commerce-destroyers,' so called. The two armored ships so named cost nearly $7,000,000—a sum nearly equal to the entire endowment of Harvard University—while the annual expense of keeping the two in commission is nearly as great as the pay roll of the same university. The only commerce of any importance upon which these destructive ships of war could exert their force would be that of Great Britain and Germany, our two largest foreign customers for the excess of our farm products, which would rot upon our fields if we could not sell them for export. Any commentary upon these grotesque conditions would perhaps be superfluous. As time goes on this waste of preparation for war will be stopped in more than one way. First, because no ship can carry armor which will defend it from the latest type of guns. Next, because no land force can stand in the face of guns discharging over six hundred shots per minute, warranted to kill at more than a mile. But lastly, as to European states, because the limit of taxation has been reached. New taxes can not be invented and new sources of revenue can not be discovered which will warrant even the maintenance of existing armies and navies."

Two Wild Vegetables of Merit.—T. W. Card, of the experiment station at Lincoln, Nebraska, calls attention, in Garden and Forest, to two wild vegetables which he thinks merit the attention of cultivators.

One of these, which is already gathered from the fields and used to a considerable extent in the West, is the wild lettuce; there are two species common on the plains, Lactuca canadensis and L. Ludoviciana. They are chiefly used for greens, and fill an important place for this purpose, as they come in advance of spinach, and when no other greens are offered in the market. The other plant is the ground plum or buffalo pea of the plains (Astragalus crassicarpus). This is found abundantly in the draws or low grounds of the unbroken prairie. The plant is a perennial, apparently perfectly hardy, and very productive. The fruit resembles gooseberries in size and general appearance. It is borne in numerous clusters, very early in the season. When cooked like string beans the fruit forms a very acceptable dish. The chief point which recommends the plant for cultivation is the time at which the fruits are ready for use, some of them ripening as early as May 7th.

Protecting Iron and Steel against Rust.—Gesner's method, described in La Revue Scientifique, consists in forming on the surface of the metal a double carbide of hydrogen and iron. A bar thus coated can be bent through an angle of forty-five degrees without disturbing the layer. The process is as follows: The surface to be coated is first thoroughly cleaned from rust. A couple of gas retorts are placed alongside each other and raised to a temperature of from 600° to 700° C. The articles to be treated are then placed in these retorts for about twenty minutes, after which a current of hydrogen is passed through the retorts for forty-five minutes. A small quantity of naphtha is then introduced, the supply being maintained for ten minutes. It is then stopped, the current of hydrogen being kept up fifteen minutes longer, when it is stopped and the retorts are allowed to cool to 400° C., and when this temperature is reached the doors can be opened and the finished product removed. The coating thus given has a bluish color.

The Microscope in Metallurgy.—Micrometallography—the examination of samples of iron and steel by looking at etched or polished sections through a microscope—is rapidly taking its place in the routine work of metallurgical laboratories. It has been developed from petrography. Dr. Sorby, an Englishman, who in 1864 submitted some photographs of opaque sections of various kinds of iron and steel to the British Association, seems to have been among the first workers in this field. The process of preparing the specimens is complicated and