Democratic Sentinel, Volume 17, Number 14, Rensselaer, Jasper County, 21 April 1893 — POPULAR SCIENCE NOTES. [ARTICLE]

POPULAR SCIENCE NOTES.

The Most Efficient Type op EkfliNß. —According to Prof. Thurston’s Investigations, the most efficient type of engine may be said to possess the following characteristics, namely: The greatest practical range of commercial eoonomic expansive working of steam, the fluid to enter the cylinder at the highest admissible pressure and expanded down to a minimum economical pressure at exhaust; the wastes of heat must be made a minimum, all loss of heat by conduction and radiation from the engine to be prevented if possible; and the usually much more serious waste which occurs within the engine by transfer of heat from the steam side to exhaust, and re-evaporation without doing its projier work must be checked as completely as practicable — this latter condition as well as commercial considerations limiting the degree of expansion allowable, as it also dictates the high speed of the engine; the largest amount of work must be done by the engine that it is capable of performing with due regard to the preceding desiderata—this rule rendeiing it necessary to drive the engine up to the highest speed and to adopt the highest practicable mean steam pressure. Are the Materials of the Earth and the Sun Similar?— In a recent discussion before the British Institution of Mechanical Engineers of the theory that the earth must be composed of the same materials as the sun, it was urged that such a view receives striking confirmation from the spectroscope, by means of which instrument it has been demonstrated that there exist in the sun mnny of our metals, particularly iron, in the state of vapor—while meteoric stones, which belong to the same order of substances as the planets, have been found, by actual analysis, to be largely composed of iron and its carbides. Again, the law of the diffusion of gases would lead to the presumption that on the condensation of the metallic vapor the substances of higher specific gruvity, or greater atomic weight, would collect chiefly near the centre of the future globe, while the lighter matters would tend to aggregate on the surface; and, as the mean specific gravity of the earth is about five, while that of its superficial deposits ranges from only two and onehalf to four, it is thought to be evident that the interior of the globe must be composed of substances having high specific weights, such as iron, for example, which ranges between seven and eight. Moreover it is certain that the rocks at a comparatively short distance down from the surface exist in a highly heated if not in a molten condition.

Sending Writing and Photographs over an Electric Wirk.--Aii exhibition of tho workings of the Gray telautograph was given to newspaper men at the offico of the company on tho seventh floor of No. 80 Broadway, New York, last Tuesday. The invention is different from the telephone in that the latter transmits speech, while this later dovice enables a sender to write at ono end of any oomplete circuit and his handwriting is reproduced in foc-siraile at the other: thus tho sonder and receiver each lias a record of every message and reply. If the receiver is absent when the message is sent he will find tho messago on his return. One advantage is tho secrocy which its work insures. Tho sender sits in his office; he calls up the central office and oaks to be put in communication with a certain number. This done lie writes upon a scroll on the top of the instrument, and as he writes hits handwriting and signature are reproduced upon a similar scroll placed before the receiver ot the other end. Meanwhile the operator in the Central is ignorant of what is passing between the persons in communication. An artist in like manner can transmit a sketch. An'ordinary lead pencil is used by the sender. The receiving pen at the other end of the circuit moving simultaneously with the pencil of the sender, is a cupillary glass tube, placed at the junction of two aluminium arms. The pen is supplied with ink which flows from n reservoir through a small rubber tube placed in one of these arms. Elisha Gray, of Highland Park, 18., is the inventor. T. M. Logan, of New York, is President of the Company. Tho factory is at Highland Park, 111.