Слике страница
PDF
ePub

THE NEW VPK PUBLIC LIBRARY

ASTOR, LENOX

TILDEN FIL ATIC IS

1

A PRINTING TELEGRAPH

273

Other Useful Inventions

An invention which first came prominently to the attention of the public in 1901 was the Murray-Page printing telegraph. This remarkable mechanism was the work of a young Australian, Donald Murray, who brought it to the United States, after unsuccessful attempts to introduce it in his own country. It was taken up experimentally by the Postal Telegraph Company. At the transmitting station the message was first transcribed on a typewriter, which perforated a tape with little holes, the position of the perforations determining the letter, in accordance with a code worked out by Mr. Murray. The perforated tape was passed through a transmitter similar in design to the Wheatstone transmitter. At the receiving station the message was received in the form of a perforated tape exactly like the one which had been placed in the transmitter. This tape was run through a typewriting machine, the keys of which were controlled through the perforations in the tape, and the result as seen on the message blank, was the typewritten message.

Each letter occupied a space of just half an inch on the transmitting or receiving tape. And this half-inch space contained five equal subdivisions, which were either perforated or not, according to the letter to be transcribed, the difference in the number and succession of the perforations and blank spaces determining the characters. The receiving machine reproduced on its tape the perforations of the transmitting tape by an electro-magnetic device.

Astonishing speed was developed by the Murray system. In a test over a line between New York and Chicago a speed of 102 words a minute was sustained. On a short line the speed was worked up to 124 words a minute.

II

Many efforts have been made to develop practical apparatus for the simultaneous reproduction of the handwriting of a distant operator. Attention was directed in 1901 to the ingenious Richey telautograph, which appeared to be a long step in advance of anything that had theretofore been suggested. The receiving pen was fixed at the extremities of two links, which were attached to the arms of two rheostats, otherwise independent of each other. Each rheostat was connected through the battery with one of the two lines, and had a total

resistance of seven thousand ohms, divided into nearly five hundred steps. The current from the transmitting station, varying in magnitude in accordance with the position of the transmitting pencil, traversed the two lines which connected the sending and receiving instruments. The receiver consisted of two galvanometer movements, with controlling springs, and the spindles on which the moving coils were fixed were connected with link motion (described above) in which was the receiving pen. The result was a very accurate transcription of the transmitting operator's writing.

III

One of the interesting exhibits of the United States Patent office at the Pan-American Exposition was a new machine called the electrograph, the function of which was to reproduce a picture at a distance. It was the invention of Herbert R. Palmer, Thomas Mills, and William P. Dun Lany, and the method of operation was as follows: The transmitting sheet was a zinc enlargement of a half-tone plate. The depressed portions of the plate, corresponding with the etched portions of the original half-tone, were filled with an insulating material. The surface of the sheet was now partly metallic, partly insulated. The filled plate was bent around a cylinder in the transmitting machine and made to rotate. Over the surface glided a stylus, which traveled along the cylinder on a carriage, much as does the reproducing stylus of a phonograph. The stylus described a continuous spiral on the surface of the plate. On the receiving instrument, perhaps many hundred miles distant, a piece of paper was wrapped around a cylinder and over its surface glided an inked pen, which touched the paper and made a line or dot only when the transmitting stylus came into contact with an uninsulated portion of the zinc plate and thus completed an electric circuit. When the stylus was in contact with the insulated parts of the zinc plate the circuit was broken and the pen of the receiving instrument drew back from the paper. In a comparatively short time the reproduction could be completed.

The same instrument was used for receiving or sending, the substitution of paper and pen for zinc plate and stylus transforming the transmitter into a receiver. The instrument worked successfully during tests over a telegraph line nearly eight hundred miles long, a picture being sent at the rate of one inch a minute.

[blocks in formation]

An invention which promised to be of considerable practical use. was the topophone, constructed by Lieutenant-Colonel D. P. Heap, lighthouse engineer under the United States Government. Two acoustic receivers or trumpets were supported by a vertical shaft. Rubber tubes extending from the lower ends of the trumpets were connected one with each ear of the person using the instrument. The shaft was then held so that the trumpets were above the head of the listener. If a sound was heard, say, in the right ear, it was clear that the sound came from the right side. The trumpets were then directed to a point where, with slight turnings, the sound might be heard successively, first in one ear, then in the other. The approximate direction of the sound could thus be determined.

The topophone was designed for the use of mariners in foggy weather. Having once discovered the direction of a sound, a ship's officer, knowing the speed of his vessel, could very quickly, by keeping the topophone pointed toward the direction whence the sound came, plot the location of the sound with sufficient practical accuracy.

CHAPTER IV

THE WAR AGAINST DISEASE

The Nineteenth Century witnessed a great advance in the treatment of disease. What had been on the part of man a mere desultory defensive struggle against the ills that flesh is heir to became more like organized warfare. It began to be prophesied freely that, before another hundred years had passed, tuberculosis, Asiatic cholera, bubonic plague, yellow fever, and many other dreaded diseases would have lost their terrors. The plan of campaign was doubtless to include the extermination of the fever-laden mosquito, a thorough application of sanitation, and the use of numerous preventives. The newly conceived idea was to keep man in health rather than merely to cure him of diseases after they had been contracted.

In June, 1901, it was announced that John D. Rockefeller had placed two hundred thousand dollars at the disposal of an American institution for medical research, which was shortly to begin work. The foundation was incorporated as "The Rockefeller Institute for Medical Research." The gift was intended by its donor to serve not as an endowment but as a fund to cover the cost of the first investigations and experiments. Doctor W. H. Welch, Professor of Pathology in Johns Hopkins University, was made president of the new institute. Associated with him on the board of directors were six other men of renown in medical science.

The Rockefeller Institute and similar organizations which already existed in other countries were, in a sense, Boards of Strategy in the campaign against disease. At their inception it was hopefully expected that they would plan the movements of the cohorts of science and continue indefatigably at their task until the last microbe had surrendered,

« ПретходнаНастави »