Page:Popular Science Monthly Volume 4.djvu/527

Rh by their number (585), we find the mean length of the shoots to be about two inches. The average number of leaves on each inch of a number of shoots, taken at random, was 34, so that the total number of leaves on these 585 shoots may be set down at 39,814. Assuming each leaf to be only one inch in length—which is considerably under the mark, even when all the small, undeveloped leaves are taken into consideration—we should have for the leaves a length of about 3,501 feet, so that, in round numbers, we may say that, including the shoots and leaves, the growth in length alone of this very moderate-sized young tree, during this season, has amounted to the prodigious number of 3,600 feet; and, if the shoots and the leaves could all be placed end to end in a continuous line, they would extend considerably more than half a mile.

Action of the Sand-blast.—At a recent meeting of the British Microscopical Society, Mr. Wenham exhibited a piece of glass "ground" by the sand-blast process, which, under the microscope, presented a very different appearance from common ground glass. It is found that the glass or other material, worn away by the sand-blast, is not ground away at all, but broken up by a battering action, similar to that of leaden bullets against a block of granite. Hence it is that, although, by the usual grinding process, ordinary sea-sand can make no impression on corundum, a blast with a pressure of 300 pounds to the square inch will perforate it in a short time. Nay, even the diamond itself may thus be speedily worn away.

A polished glass surface, exposed for an instant to the sand-blast, shows an aggregation of points of impact, from which scales of fractured glass have broken away in an irregular radial direction. It appears as if a pellet of glass had been driven in by the collision of the sand, and the wedge-like action thus set up had driven away the surrounding glass. All these spots, or indentations, when tested by the polariscope, show a colored halo round each, proving that the glass surface is under strain and ready to yield to further fracture. The action, therefore, is not so much due to the hardness of the striking particles as to the force and velocity of impact. This is sufficiently great to destroy the cohesion of the material operated upon. The external layer is carried against the under stratum, and the material is crushed and disintegrated by a portion of its own body.



gives a tabulated statement of the mortality of the various States of the Union, from which we borrow the following regarding the death-rates of various cities: The highest death-rate in 1872 was exhibited by Memphis, where the deaths were 46.6 in each 1,000 inhabitants. Other cities followed in this order: Savannah, 39.2; Vicksburg, 36.5; Troy, 34; Hoboken, 32.9; New York, 32.7; Newark, 31.6; New Orleans, 30.6; Boston, 30.5. The rate for Philadelphia was only 26.1; Brooklyn, 28.1; St. Louis, 20.1; Chicago, 27.6; Baltimore, 25.1; Cincinnati, 20.5; San Francisco, 17.2. This compares not unfavorably with the mortuary statistics of British cities, where the lowest rate was 21.4; that of London, Bombay, and Calcutta, show only 29.2 and 25, respectively. The highest known death-rate prevailed in Valparaiso, Chili, 66.9.

the vine with pure essence of Eucalyptus globulus is said to be an effectual remedy for the phylloxera or grape-vine disease. The mode of applying the remedy is this: a broad incision is made through the bark at the neck of the vine, in which a few drops of the essence are deposited by means of a small camel's-hair brush. In about three days the phylloxera insect entirely disappears, while the vine is not in the least injured by the operation.

practice of ringing and tolling bells by swinging the clapper or tongue violently against the side of the bell while the latter is stationary, is said to be a very frequent cause of fracture. The bell itself should always be in motion when struck by the object that is intended to set it vibrating.

, says the Mining and Scientific Press, are largely utilized in Europe. They are converted into a kind of wool or wadding, which is used for upholstery instead of hair. A kind of flannel is also made from this fibre, which is said to be very superior for many hygienic uses, as for rheumatism and skin-diseases. Vests, drawers, loose shirts, etc., are also made of this material. In the process of manufacture an ethereal oil is obtained, very useful as a solvent, and as a curative agent. Gas is made from the refuse, and used for lighting the manufactories; or the entire refuse may be