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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