Democratic Sentinel, Volume 17, Number 31, Rensselaer, Jasper County, 18 August 1893 — POPULAR SCIENCE NOTES. [ARTICLE]

POPULAR SCIENCE NOTES.

A new glass for thermometers is unaffected by a heat of 1,000 degrees, the ordinary glass being unreliable above 750 degrees on account of its tendency to soften. A pneumatic tube connects Paris with Berlin. It is used for postal purposes, and makes it possible for a letter mailed in Paris to be delivered in Berlin in thirty-five minutes. Taking Electricity From the Ain.— Mr. Palmicri, in La Lumicre, describes an apparatus for collecting atmospheric electricity. It consists essentially of a revolving wheel having eight spokes, but no rim; each spoke is made of a conductor insulated from the hub and having a small metallic cross-arm at its further end; near the hub are nrrauged two brushes, one above and one below the center; these brushes are always in contact with the spokes pointing vertically ‘upward and vertically downward respectively, during the revolution, and therefore lead off from them the electric charges collected from the atmosphere at the top and at the bottom of the wheel; the brushes are connected by wires to two I.eyden jars and to sparking knobs as usual.

A Burning Glass Made of Ice. —A few years ago an English professor caused quite a little excitement dmong a party of skaters on Serpentine River by making a lens of ice and lighting his pipe with it. This reminds the writer that this curious experiment was first brought before the public by the great Dr. Scoresby, who, when in the polar regions, to the great astonishment of his companions, who did not understand why the ice did not freeze the solar rays, performed a similar feat. It may also be worthy of remark that Professor Tyndall, when a teacher in the Royal Institute, on several occasions set fire to little heaps of powder with rays from an electric are concentrated by a lens of ice. His explanation was this: although ice absorbs rays of certain waves of light and is gradually melted thereby, there are other kinds of waves which it does not absorb, and it is these that produce heat at the focus of the bar of light which passes through the ice. In short, it is wholly a question of the relative motions of the molecules of frozen water and those of the waves of the more penetrating rays of light.