The Crystal Foreshadows the Plant.
One of the remarkable attributes of a crystal is its ability to grow and act as a unit, as if it had a life of its own, despite the evident variety and great number of its parts. Take a crystal of alum, break off a corner and then immerse the broken mass in its mother liquor; at once the crystal will repair itself, new molecules building themselves into its structure as if they knew where to go. This unity of effect may be observed during a northern winter on a scale much more striking. In cold weather on a large sheet of plate glass exposed as a window, a frost pattern will extend itself as if a tree, beautiful branches spreading themselves from a main stem which may be seven feet in height. It is altogether probable that polar forces, such as we observe in the magnet, are here at work. Their harmony of effect, in spaces comparatively vast, is astonishing. Forces of allied character rise to a plane yet higher in vegetation, culminating in the magnificent sequoia of California, whose life, measured by thousands of years, goes back almost to the dawn of human civilization. The union of tools, levers, wheels, as an organized machine; the co-ordination in research of the parts to be played by observers, recorders, depicters, generalizers; the regimentation of soldiers, so that all march, advance and fire as one man under the control of a single will, is prefigured in the forces which make a unit of every crystal of saltpetre in a soldier’s cartridge-box. Of all the characteristics of matter none is more pervasive and more marvelous than its ability to form a unit which moves and acts as if no part were separable from any other, while manifesting a highly complicated structure, with functions at once intricate and co-ordinate.
A
Alum crystal.
B
After a part has been
broken off.
C
Restored by immersion
in alum solution.
From photographs by Herr Hugo Schmidt, Hackley School, Tarrytown, N. Y.
During Long Periods Minute Influences Become Telling.
Qualities of matter, much more simple, may now engage our attention. First, then, let us note how minute influences, acting for long stretches of time, may change the qualities of metals and rocks. Forces, too slight for measurement as yet, are known in the course of a year or two to affect steel at times favorably, at other times unfavorably. The highest grades of tool-steel are improved by being kept in stock for a considerable time, the longer the better. It seems that bayonets, swords, and guns are liable to changes which may account for failure under sudden thrust or strain. Gauges of tool steel, which are required to be hard in the extreme, are finished to their standard sizes a year or two after the hardening process. Slow molecular changes register themselves in altered dimensions. In the Bureau of Standards at Washington are a yard in steel and a yard in brass, at first identical in length; after twenty years they were found to vary by the 1⁄5000 of an inch. Take another case, familiar enough to the railroad engineer: in a mine, or a tunnel, the roof or wall may tumble down a month or more after a blasting. The stone which fell immediately upon the explosion was far from representing all the work done by the dynamite. A stress was set up in large areas of rock and this at last, beginning in slight cracks, overcame the cohesion of masses of huge extent.
