Beyond their unending study of forms and properties, their constant weighing and measuring, the inventor and his twin-brother, the discoverer, have a gainful province which now for a little space will engage our attention. This province is nothing else than Nature, which begins by offering primitive man stones for hammers, arrowheads, knives; sticks to serve as clubs, paddles, harrows or tent-poles. We may well believe that the lowest savages have always exercised some degree of choice even here; it would be the soundest and sharpest stone that they picked up when a rude axe was needed. Should only blunt stones be found, then in giving one of them an edge was taken a first step in art, rewarded with a tool as good as the axe found ready to hand in some earlier quest. Nature is not only a giver of much besides stones and sticks, she is virtually a great contriver whose feats may incite the inventor to reach her goals if he can; his path will probably differ widely enough from hers as he arrives at success.
Forces Take the Easiest Paths.
When one drop of rain meets another, and they join themselves to thousands more on the crest of a hill, they need no guide posts to show them the easiest course to the valley. They simply take it under the quiet pull of gravity. When a bolt of lightning darts across the sky, its lines, chaotic as they seem, are just the paths where the electric pulses find least obstruction. If a volcano, which has boiled and throbbed for ages, at last opens a chasm on a hapless shore, as that of Martinique, we may be sure that at that point and nowhere else the mighty caldron’s lid was lightest. A cavern in Kentucky, or Virginia, slowly broadening and deepening through uncounted rills which dissolve its limy walls, comes at last to utter collapse: the breach marking exactly where an ounce too much pressed the roof at its frailest seam. In these cases as in all others, however complex, matter moves inevitably in the path of least resistance. To imitate that economy of effort is from first to last the inventor’s task.
Cities and Roads.
Rains, winds and frosts, in their sculpture of the earth have each taken the easiest course; in so doing they have incidentally marked out the best paths for human feet, have pointed to the best sites for the homes of men. The stresses of defence may rear a pueblo on the peak of a perpendicular cliff in New Mexico, but Paris and London, like Rome, must have all roads leading to their gates; and the easier and shorter these roads, the bigger and stronger the city will become. Where New York, Montreal, Chicago, and Pittsburg now stand, the Indians long ago had the wit to found goodly settlements. They knew, as well as their white successors, the advantages of paths readily traversed, and no longer than need be. In this regard there was an instructive contrast at the outset of railroad building in England. A leading engineer, who planned some of the earliest English railways, had strong mathematical prepossessions: he endeavored to join the terminals of his routes by lines as nearly straight as he could. George Stephenson, for his part, had no mathematical warp of any kind, but instead much sound sense; his lines followed the courses of rivers and valleys, and kept, as much as might be, to the chief indentations of the sea. His roads deviated a good deal from straightness, but they did so profitably; whereas the lines of his academic rival, disrespecting the hints and indications of nature, were much less gratifying from an investor’s point of view. If a traveler takes the New York Central and Hudson River Railroad from New York to Buffalo he goes north for 143 miles, to Albany, before he begins to travel westward at all. Yet this line, keeping as it does to the well-peopled levels of the Hudson and Mohawk Valleys and serving their succession of cities, towns, and villages, enjoys the best business, and makes better time between its terminals than any rival route, because it passes around instead of over its hills and mountains. By way of contrast we turn to the railroad map of Russia and observe how Moscow and St. Petersburg are joined by a line which follows the road which it is said that Peter the Great, with military exigencies in view, laid down with a pencil and ruler.
Deciduous cypress, Taxodium distichum.
Engineering Principles in Vegetation.
If the engineer has many a golden hint spread before him in the hills and dales, the streams and oceans of the world, not less fruitful is the study of what takes place just beneath the surface of the earth where the roots of grain and shrub, reed and tree, take life and form. Plant a kernel of wheat in the ground and note how its rootlets pierce the soil, extending always from the tip. They need no gardener or botanist to bid them lengthen and thicken where food chiefly abounds. In an arid plain of Arizona a vine, in ground parched and dry, goes downward so far, and spreads its fibrils so much abroad, as soon to show ten times as much growth below the drifting sands as above them. In fertile, well-watered soil the same vine descends less than half as far, and yet with more gain. A bald cypress in a swamp of Florida responds to different surroundings with equal profit. Finding its food near the surface its roots take horizontal lines, at no great depth in the soil. Every wind that stirs these roots but promotes their thrift and strengthens their anchorage. A wealth of sustenance floats in the swamp water. In seizing it and being thereby fed, the roots develop “knees”; these brace the tree so firmly against tempests as to win admiration from the engineer. When the progeny of this cypress grow on well-drained land, the knees do not appear, while the roots within a narrowed area strike deep. Thus simply in doing what its surroundings incite it to do, the tree acts as if it had intelligence, as if it consciously saw and chose what would do it most good.
