Page:Popular Science Monthly Volume 47.djvu/875

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The last two are the anchylosed phalanges mentioned above. The subject under discussion has one brother similarly affected, whose webs are decidedly larger than in the present instance. This brother has but one stiff joint on each hand. The father has hands somewhat webbed. A second brother has no webs, nor has the mother, nor the paternal or maternal grandparents.

How Stone Arrowheads were Made.—The guiding principle of Mr. F. H. Cushing's fruitful researches in anthropology has been "Put yourself in his place." When he wished to learn how stone arrowheads were made he became an arrow-maker himself. As a result of his labors and researches he was able to tell, in his address to the Anthropological Section of the American Association at Springfield, how primitive men made their arrows. They first sought the material, he said, mined it arduously from buried ledges, with fire, mauls, and skids, or preferably sought it in banks of pebbles, digging such as were fit freshly from the soil, if possible, and at once blocking out from them blanks for their blades by splitting the pebbles into suitable spalls. This was done by holding the pebbles edgewise on a hard base, and hitting them sharply and almost directly on the peripheries, but with a one-sided twist or turn of the maul or battering stone. At each deft stroke of the maul a spall was struck off—sometimes twenty from a single cobble or block of moderate size. These were, with almost incredible rapidity, trimmed to the leaf-shaped basis of all primitive chipped tools, by knapping them with a horn, bone, or very soft, tough, granular stone hammer, mounted in a light handle. For this the spall was placed flatwise on the knee, or on a padded hammer-stone, so called, and held down by the base of the thumb of one hand, and rapidly struck along the edge transversely and obliquely to its axis, lengthwise, with the outwardly twisting kind of blows used in the splitting. The blanks thus formed were then carried home for leisurely or opportune finishing; and carefully buried in damp soil, not to hide them, as has been usually supposed, but to keep them even-tempered, uniformly saturated or full of sap and life, as these ancients thought—whence the so-called "caches" of numerous leaf shaped blades which are now and then found throughout old Indian ranges. To show that making arrowheads is not such a slow and laborious process as many have supposed Mr. Cushing stated that he had succeeded from the time he found a suitable pebble of fine grained, ringing, cold and fresh quartzite, in making seven finished knife and arrow blades in exactly thirty-eight minutes; and he had often made from obsidian or glass a very small and delicate arrow point—the most easily made—in less than two minutes.

Chemistry advanced by the Industries.—In showing how pure science had been promoted by industrial operations and requirements, which was the theme of his vice-presidential address before the American Association, Mr. William McMurtrie cited an interesting example from Hoffmann, who says, "It is not generally known that the theory of substitution owes its source to a soirée in the Tuileries." Dumas had been called upon by his father-in-law, Alexandre Brongniart, who was director of the Sèvres porcelain works, and, as Hoffmann says, in a measure a member of the royal household, to examine into the cause of the irritating vapors from candles burned in the ballroom, a demand to which Dumas readily acceded, because he had already done some work upon the examination of wax which could not be bleached and was therefore unmerchantable. He was readily led to the conclusion that the candles used in the palace had been made with wax that had been bleached with chlorine, and that the vapors were hydrochloric acid generated in the burning of the candles. But examination of the wax of the candles showed that the quantity of chlorine found was greater than could be accounted by for its presence as a mechanical impurity, and from it Dumas was led to experiments which showed that many organic substances when heated with chlorine have the power to fix it, and from these results he was in turn led to the further generalization concerning the law of substitution. It was an incident similar to that