Popular Science Monthhi 



Below : T h e 

 parts of the 

 transmitter. 

 Simple con- 

 struction is 

 possible since 

 out side 

 framework is 

 unnecessary 



Electrodes mount- 

 ed directly on 

 diaphragm Car- 

 bon granules 

 ar& between 



Mica disc 



Diaphrag 



: Lead in wire 



Cover cap 



Carbon 4 

 granules 



The girl is holding the 

 bare diaphragm in her 

 hand and easily carry- 

 ing on a conversation 



At Last ! A Noise- 

 less Telephone 



TRANS- 

 MITTER ^ 

 inventions there 

 have been with- 

 out end, but one v_^ 

 which promises 

 to dispose of side tones is being put out 

 by a Chicago company. Side tones are 

 troublesome hums, rattles, jars, and vi- 

 brations which make it impossible for a 

 person to carry on an uninterrupted 

 conversation. The principal cause for 

 the presence of these 

 extraneous noises is ^n 



the fact that the 

 whole outer case of 

 the transmitter is 

 receiving the sound 

 vibrations; and, since the 

 inner parts of the instru- 

 ment are all held and 

 trussed in place by cross- 

 pieces fastened to this case, 

 the result is an interclashing 

 of noises which cannot help 

 but interfere with conversation. Every 

 piece of metal — or object, has its own 

 natural period of vibration; that is, it 

 is peculiarly susceptible to certain sound 

 pitches, or other vibratory disturbance, 

 and thus it responds readily when 

 these pitches are reached. Sensitive 

 as a transmitter is, it takes notice of all 

 these vibrations. 



■Working parts 



in this recess The instrument can 



be submerged in water 

 and it will still work, 

 as illustrated above 



The Chicago inven- 

 tion would get around 

 these difficulties by at- 

 tachingtheworkingparts 

 of a transmitter to the 

 diaphragm (that round disk you 

 talk against), leaving the case free. 

 The parts are small, and consist of 

 the usual carbon granules between 

 two disks. Aside from being free from 

 side tone, the new transmitter is said to 

 be remarkably sensitive. It can be sub- 

 merged in water without in the least in- 

 terfering with the conversation. 



Even Milk Bottle Openers Are 

 Problems in Mechanics 



MILK-BOTTLE opener which does 

 not spill the milk, has been invented 

 by Oscar Frank, of Cleveland, Ohio. 

 The sharp pointed prong juts out at 

 an acute angle from a little flat bar. 

 When the prong pierces the cap, it 

 does so in an almost 

 horizontal direction. 

 The capis thus pressed 

 against the side of 

 the bottle and not 

 toward the bottom. 

 The lift of the cap 

 meanwhile takes 

 place as it slides up 

 the incline of the 

 The opener is ^^ ^^^ ^.q^. 



worked sideways ^ ^ . ,, v . .1 

 and no milk is spill- tents of the bottle are 

 ed from the bottle not spilled on the hand. 



