742 



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 



