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Page:Popular Science Monthly Volume 89.djvu/939

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Popular Science Monthly


��Making the Vibrations of the Voice Draw Designs

ONE of the must iiitrtLsting of modern scientific devices is the eidophone. By- means of this instrument it is possible to

secure impres- sions of sound

vibrations in a

curious and

often beautiful

form. It is real- ly easy to make

a box which will

enable one to

draw patterns

with the voice.

A glance at the


illustrations will

show that the

things necessary

to produce this

contrivance are

few and simple.

A tin saucepan of moderate

with a hollow handle, an

metal funnel will be re- quired. These may be

found about the kitchen

of almost any home. The ^

only necessary thing to

purchase is a piece of

sheet-rubber large

enough to stretch over the top of the saucepan. Any kind of thin rubber sheeting will do, but the best for the purpose is that commonly employ- ed for the making of toy balloons.

With these materials gathered together start to make the device by opening up the handle of the saucepan. Any sharp metal tool may be used to pene- trate the tin and the opening should be the same size as the inside diameter of the handle, so that it resembles a tube. Push the funnel-end well down into the inside of the handle. The rubber sheeting is spread over the opening of the saucepan and tied down firmly at the sides with a string. It is important to draw the sheeting until it is as taut as the head of a drum. The eido- phone is then ready for use.

To make the experiments, some kind of a, very light powder must be used. Ver>' fine sand, precipitated chalk, or lycopodium powder, procurable at most drug stores,

���are all good. Whatever material is used should be spread in a thin layer on the rubber surface; then start to sing into the funnel a monotone note, steadily and continuously. In a short time it will be seen

thattheparticles of the powder arc busily arranging themselves into a design, which varies quite per- ceptibly accord- ing to the note sounded and the material used for the powder. An endless num- ber of fascinat- ing experiments can be carried on in this way. Colored glycerin can be used also, which when spread on the rubber will pro- wavy patterns as the note is sounded in the tube. The only point to bear in mind is that in changing the substance on the rubber all traces of one material must be re- mo\ed before another is put on. — S. L. Bastix.

��The vibrations set up by the voice produce beautiful designs in powder, chalk or glycerin on the rubber surface

��Friction Tape Used for Plaster Strips

A "shop doctor " is called upon many times to bandage an injury while waiting the call of a regular physi- cian. Adhesive tape is not always at hand, but usually some "friction" or "electricians' tape" maybe had and can be used instead. This tape was tried out to keep a dressing on an ulcer on the heel of a sailor's foot during a long cruise. Almost the entire foot was well wrapped so that the man was enabled to walk the deck in his bare feet even when washing down. The tape being adhesive on one side provided a covering that was almost water-tight.

This tape has also been used in emer- gencies to make covers for dressing over hands and wristlets for sprained wrists. It is not preferred to zinc oxide adhesive tape but is ^•aluable where the other is not at hand. — Dr. Otto So.m.mer.

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