Page:Popular Science Monthly Volume 89.djvu/756

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��Popular Science Monlhhj

���Hold a microphone against your back and it will pick up the sound of your voice

Hearing Your Voice Through Your Bones

AFREXCH specialist, Dr. Julos Glover, has dcxisetl a nu'lhod of picking up the vihrations ot the \oice in the hones and tissues of the body. He employs a galvanometer — in otluT words, a sensitive current-measuring de\ice — in the circuit, with which is a microphone or sound-detector, the ])rim- ary of an induction coil, and a liattery connected with a voltameter. The mi- crophone is placed against the subject's liody, so that it can lie alTecled only after the \ice has vibrated through a dense layer of bones and muscle. The \oice is not actually heard, but rather visualized, since the gaKanometer-needle swings out of its course as soon as the current llowing through the circuit is changed in the slightest. The current is so changed because the \-ibra- tions alTect the microphom in the circuit from momeni \n moment. H\- iM(hi<ling telephone rtcei\'ei"s in tlu- f\^^ driver circuit of. the secondary of and speed

��the coil, and fastening them to his ears, 1 )r. CIlo^•er also hears the sounds pass- ing through the body.

I )r. (jlo\er claims that his system renders it possible to take a patient's pulse far more accurately than is possil)le with the hand alone. He can count the beats both as they appear as ffuctuations of the galvanometer-needle or as rhythmic clicks in the telephone receivers. Variations undetected b\- the hand are immediately obsc r\td. In this case the microphone is employed as a transmitter.

A Motor-Wheel for the Railroad Velocipede

RHJ)IXG the rails ona\elocipedepro- . pcled by a motor-wheel, the track- man traveling to make repairs has a s])ecial car of his own just as the railroad jiresident has. For a gotnl many yeari; the trackman hashadhis\elocipedeand has hand-i)um|)e(l it up hill and down dale until all no\ elt\connccteil with the vehicle has long since been forgotten. With the introduction of the motor- wlieel, however, he is again in the lime- light. He can recline in his seat, operate the motor, and sail o\er the tracks with- out any expenditure of energy.

The motor-wheel can be attached to the veloci|)ede and taken off withoiu making any alterations. A casting which tits between the two lower rails of the \elocipcde serves as the comiecting unit. It holds the motor-wheel sccureK' in ))lace, so that it cannot move either to the right or left, but stays constantly on the balls of the rail. The attachments ])ermit of the free moving of the wheel.

���can rcchne in his scat, oi>cratc llic motor over the trucks without expending energy

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