Popular Science Monthly 



925 



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 



accompanying 



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. 



