Page:Popular Science Monthly Volume 92.djvu/483

 �Q AmatGur ■ Eloctrician

��i^d Wii'Gless Operator

��A Speed Indicator Will Count the Turns for Your Coil

IN winding coils on a small lathe, a speed indicator may be used to count the number of turns. As the only means of connec- tion furnished with the

���indicator are a number of rubber tips, it is difficult to fasten the indi- cator to the lathe spindle. This diffi- culty may be over- come by using a

��Speed indicator on a small lathe spindle

��rubber tube as shown in the illustration. If the lathe spindle is too large, whittle a wooden plug with a peg on the end to fit in the hole. — Edward McClure.

��The Electro-Deposition of Copper on Insects and Flowers

MANY interesting specimens can be permanently preserved by the fol- lowing process, which is both inexpensive and simple.

Melt together 110-115 grams each, of wax and deer's fat, and add 10 grams of phosphorus dissolved in a solution of 150 grams of carbon disulphide. Be careful to keep the phosphorus and carbon disulphide solution away from the flame, for the mixture is explosive.

When it has nearly cooled, stir it thoroughly and then pour it carefully through a glass tube, or preferably a glass funnel, under the surface of the fatty substance. The articles to be plated

��are attached to a wire and dipped in the mixture. Then they are given a bath in a solution of dilute nitrate of silver. When the silver turns black, the articles should be rinsed in water, and immersed in a weak chloride of gold solution, after which they are again washed. Now that they are coated with a film of gold, the articles are ready for the coppering solution. — Herman Neuhaus.

��An Electric Bell Signal to Indicate Falling Snow

WITH many square feet of sidewalk to keep free from snow, I have found the device illustrated, helpful to warn me of any unexpected snowfall during the night.

Between two upright boards, about 12 in. high by 6 in. wide, I suspended a piece of silk, connecting each end with

, Black silk cloih sprinkled

■/•. .—, .VlfltfT SOtt-

���Silk cloth between supports to catch snow for making indoor electric connections

a bell and battery in my bedroom. The silk is a non-conductr>r when dry, but when snow falls and wets it, the circuit is completed and the bell rings. To facilitate the melting of the snow the silk should be well sprinkled with com- mon table salt.— F. E. Brimmer.

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