Page:Popular Science Monthly Volume 37.djvu/591

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A mode of filling teeth that has recently been made practical in England is by inlaying porcelain. The cavity is made perfectly cylindrical, and a bit of specially manufactured porcelain is turned to the exact size to fit it. The inlay is then secured in its place with sandarac varnish or very fluid white filling. After this is set, the surface of the inlay is ground to a proper contour and polished. An oblong cavity can be filled by inserting two inlays. Of course, this method can not be used, nor is it specially desirable, for all cavities, but few will deny that a filling which matches the natural tooth in color is far less conspicuous, and more agreeable to see, than the glaring patches of yellow metal, which are only excusable as saving a worse disfiguration.

The sum of six hundred dollars has been appropriated by the National Academy of Sciences for the construction of apparatus to aid Prof. Cattell in his researches on the time of cerebral operations. With the cooperation of Dr. S. Weir Mitchell, Prof. Fullerton, Prof. Dalley, and others, researches are in progress at the University of Pennsylvania on the rate at which impulse travels in motor and sensory nerves and in the spinal cord, the time of reactions and of more purely mental processes, memory and the amount forgotten in a given time, the time of bodily and mental processes in diseases of the nervous system, and in other directions.

The effects of steam in the destruction of bacteria do not depend, according to the researches of Von Esmarch, so much upon the temperature as upon the degree of saturation of the steam. If there is air with it, the power of destroying organic germs is very much diminished.

A committee has been formed in Paris for the erection of a statue of the late M. Boussingault.

During some experiments as to the temperature of snow at different depths, it was found that very little variation occurs in the lowest layer, next the ground, while the temperature of the upper layer is considerably higher.

A novel aspect of bacterial life is suggested by A. de Barry in his Comparative Morphology of the Microfungi. Writing of Bechamp's theory of the microzymes, the author says that these minute bodies not only develop independently after the death of the parent organism, but enjoy an almost unlimited duration of vitality, since they may lie during entire geologic periods in such a rock as chalk, and yet retain the power of development.

Dr. R. Assmann, in a communication to Das Wetter, names, with especial reference to influenza, as the climatic conditions favorable to the dispersion of organisms in the air: Dryness of the ground and absence of snow; infrequent rain and that light; presence of fogs or low clouds; and predominance of high barometric pressures, with imperfect intermingling between the strata of the air.

Celluloid artificial eyes are cheaper than those of glass and have a good appearance; but Dr. Meurer, of Lyons, states that after three or four months they are liable to cause serious irritation, probably as a result of some chemical change. He has repeatedly seen this inflammation allayed by simple antiseptic treatment after the removal of the celluloid, reappearing, however, as soon as the old eye was put in again, but remaining absent if a glass eye was substituted.

The Scientific Publishing Company, New York, announce as in preparation Systematic Mineralogy, based on a Natural Classification, by Dr. T. Sterry Hunt.

The French Association for the Advancement of Science will hold its nineteenth annual meeting at Limoges, from August 7th to 14th. A number of English scientists have been invited, who will be guests of the municipality of Limoges.

In a recent article on cyclones, Mr. H. Habernicht shows that, if the globe were covered with water, the general circulation of the air would be very regular. He states as the primary cause of cyclones the obstruction offered to the wind by the continents to the east and west of the Atlantic; and, secondly, the constant high barometric pressure over the continent and in the arctic regions during the winter.

Dr. Fitch, former State Entomologist of New York, gives a remarkable instance of the long imprisonment of insects without loss of life. In 1786 a son of General Putnam, residing in Williamstown, Mass., had a table made from one of his apple-trees. Many years afterward the gnawing of an insect was heard in one of the leaves of this table. The noise continued for a year or two, when a large, long-horned beetle made its exit therefrom. Subsequently two more beetles issued from the same table-leaf, the first one coming out twenty and the last one twenty-eight years after the tree was cut down.

Some recent explorations in the famous Adelsberg cave, Carniola, Austria, show that the Ottaker cave discovered last year is a continuation of the larger one. The exploration was made by a party of Adelsberg citizens and occupied six hours. It was necessary to use a boat several times. The explorers think the cave very much larger than was formerly supposed.

It is proposed in Paris to name a new street after Darwin.