Page:Popular Science Monthly Volume 92.djvu/263

 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.

��� �