Page:Popular Science Monthly Volume 91.djvu/121

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Popular Science Monthly

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��previously mentioned they simply cause switches back of each key to pick out the right set of lamps to blazon forth the letter it is desired to show in a given letter-block. Since the letter-blocks are arranged in long lines it is possible to spell out words and phrases, simply by causing the indi- vidual letter-blocks to show the char- acter desired. The principle is made clearer in the illus- trations.

Changes in the wording of the sign are effected as fast as the operators can work the keyboard — one man devoting his entire attention to a single line on the sign, but to- gether with his fel- lows getting orders from cardboards in the hands of the chief operator. A given message is made to flash on the sign very much as type is set up on a linotype machine. In the linotype case the printer punches

proper keys to spell out one line, strikes a lever convenient to his right hand, and the matrices pass on into the machine to mold the type while he is busying himself with the next line. In the same way, the operators of the new sign punch proper keys to spell out a given message, strike a lever, and the message flashes on the sign. While people are reading it, the men are setting keys for the next com- munication, which appears the next in- stant.

The sign was orig- inally patented by W. W. Arnold, of Hamilton, Ohio, but it has been worked out in a commer- cially practicable way by M. E. Laun- branch, an engineer of Chicago.

���A message is made to flash on a sign very much as type is set up on a linotype machine. The operators punch the keys to spell it out

��Compared with Electricity Gas Is Still the Cheaper Medium

IN spite of the decreased cost of electric service and the increased efficiency of electrically operated devices, the fact re- mains that of the two sources of en- ergy generally avail- able for heating, lighting and cooking, namely, electricity and gas, gas is by far the cheaper medium. At the present time one thousand elec- tric heat units cost fourteen times as much as one thousand gas units. Furthermore, it is impossible to cook as rapidly with elec- tric heating devices as with gas cookers. In the lighting field gas is, under certain conditions, cheaper than electricity, al- though it has not the large variety of applications that electricity has.

���A Telephone Attachment Which Per- forms the Services of a Watch Dog

RUPERT H. GREENLAW, of New York, has invented a meter attachment which is a mechanical watch-dog for your telephone. It consists of a small case containing a locking and registering mechanism, a clamp which fastens it to the telephone standard, and a rod which engages with the tel- ephone receiver. By removing the receiv- er the rod is forced in and out of the interior of the meter. It is impossible to replace the receiver upon the hook until the call has been registered.

��The attachment which locks the telephone when it is not in use and registers all calls

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