Page:Popular Science Monthly Volume 42.djvu/152

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142
THE POPULAR SCIENCE MONTHLY.

ent manufacture. The graphite was sawed into small sticks and these were inclosed in wood. The Cumberland pencil was regarded till about the beginning of our century as unsurpassed, distinguished by an extraordinary softness and delicacy in the drawing, and was extremely costly. Only the best and purest material being used, this was exhausted in a relatively short time, without any new source being discovered. At last, manufacturers began to pulverize the waste and to mix it with other materials, to press the mass into hard cakes and saw it up in the old way, without getting a pencil in any way comparable with the old Cumberland brand. New beds of graphite were, however, discovered in Bohemia, the product of which was still far inferior to that of Borrowdale. After some time the art was learned of purifying the Bohemian graphite by a careful chemical process; and toward the end of the last century the happy thought occurred at once to a French and a German manufacturer of mixing purified graphite, finely ground, with moistened clay. The invention was useful in three ways: by reducing the cost of the pencils without impairing their quality; by making it possible, through variations in the proportions of the ingredients, to give the pencils different degrees of hardness; and by simplifying the manufacture, so that pencils became cheap and within the reach of all.

 

Native Types in Abyssinia.—Traveling in Abyssinia, M. Jules Borelli was most struck with the multiplicity of the native types, and, in fact, with the entire absence of a pure type. Thus, it seemed impossible to find a regular Abyssinian type at Shoa. This is possibly accounted for by the fact that four fifths of the people at least are the sons of slaves of various origins. The sons of the daughters of nobles, who pretend to be of the pure race, are most frequently grandsons of slaves. In many places cloths and articles of silver were found, bearing designs that pointed to an Oriental origin, which seemed to indicate that, long before the rise of Islam, southern Arabia was occupied by Persians. These were the first Asiatic races which, passing the Red Sea, drove back before them the black races, while they mingled with them, forming those innumerable varieties which now make a classification of native types impossible. The multiplicity of languages spoken in these regions is another consequence of these invasions and crossings.

 

Glacial Moraines in Illinois and Indiana.—In a paper on the Glacial Phenomena of Northeastern Illinois and Northern Indiana, Mr. Frank Leverett describes the moraines as terminal to the ice, but not to the drift-covered areas of those States. Four proofs of advance in the production of later moraines are cited: Buried soils in situ between till sheets; changes in the direction of flow as shown by striæ; change in the form of the ice lobe, as indicated by the distribution of the morainic belts and the shiftings of the re-entrant and lobate portions; and evidence of push or advance found in the moraine itself. The number of distinct moraines varies because of partial coalescence or local obliteration of portions of certain moraines by later advances. For this reason correlation is difficult. Aside from this, there is an increase in complexity in passing from older to newer moraines.

 

The Stone Hand-hammer.—A special study has been published by Mr. J. D. Mc Guire, of Ellicott City, Md., of the stone hand-hammer, which he believes was probably the tool upon which races living in the stone age relied more than upon any other object to fashion other stone implements. There is no implement, he says, more common among the relics of the stone age, none the uses of which have been less discussed by archæologists, and none more deserving of thorough discussion. The objects seem to be comprised in three types: First, a flattened or oblong ellipsoid, having a pit on one or both sides, the pits being probably intended as finger-holds to relieve the index-finger from the constant jar occasioned by quickly repeated blows on a hard surface. The periphery of these will often be found quite smooth, at other times rough, according as it has been last used as a hammer or as a rubber; for, besides using the hammer to peck his axe or celt into shape, he afterward polished his implement with it. Often one or both of the flattened sides show the effect of rubbing. A second type is the spherical implement, slightly flattened at the poles, showing a battered and commonly a