Page:Popular Science Monthly Volume 92.djvu/924

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��Popular Science Monthly

��This bolt takes r^::^ the thrust \ 'I

��-J Key to shaft

V

���The ball seated//

heads take the/" \ Flexible pir\s,

reverse pMll do the driving

The center bolt gives the required rigidity to the coupling, the lami- nated steel pins of the flange give it the necessary flexibility

��Flexible Coupling Takes Side Strain Off Shafting

UNLESS there is perfect alinement of the propeller shaft with the engine or reverse-gear shaft there is sure to be trouble in any engine-propelled marine craft. Binding bearings, with resulting friction, hot journals and loss of power, or excessive vibration and consequent wear are the natural results of the side strain caused by the imper- fect alinement. As a truly perfect aline- ment is possible only in theory, some pro- vision must be made to compensate for de- fects in the alinement which may develop from various causes at any time. It was found that a flexible coupling for connect- ing the propeller shaft with the engine constituted the best remedy. One of these flexible couplings, which has been successfully tried for marine engines of various types, is here shown in cross section.

The coupling consists of two cast-iron or steel flanges con- nected by flexible lami- nated steel pins instead of rigid bolts. The con- struction of the coupling is made plain by the diagram. The center bolt takes the push or pull, as the case may be, from one shaft to the other. The flexible laminated steel pins, which connect the two flanges, allow sufficient play to give the coup- ling universal action within its intended limits. The pins take no push or pull, their business is to drive. It is expected that this

arrangement will elim- ^,^. ,^.

°, , , The student sin(>b

mate much trouble into the tubes to

hitherto encountered. test quality of voice

��E^

��A First Aid to the Singing-Teacher. It Analyzes the Voice

VERY tone of the human voice is composed of fundamentals and over- tones, according to the musical authori- ties. It is the presence or absence of the overtones which decides whether a tone is musical or otherwise. Hence overtones constitute the essen- tials of the singing voice.

Professor Howard H. Hanson, of San Jose, Calif., has per- fected a device which determines what over- tones of a particular voice need cultivating or subduing for the sake of bringing the voice up to its maxi- mum beauty. The de- vice is constructed principally of tin and resembles a huge from which tubes of

��stove-pipe jomt

various lengths and sizes protrude hori- zontally.

There are sixteen of the tubes, and each is tuned to a different overtone of middle "C." When a voice is to be tested, the student sings the five vowels on middle "C" into the protrud- ing end of a tube. The sound waves of the tone enter a resonating cham- ber where the presence or absence of the desired overtone is recorded. The test is repeated through each of the six- teen tubes and the records thus obtained clearly show the teacher on which vowel sounds most ^ork is re-

���Each of the tubes regis- ters a certain overtone of middle "C"

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