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Popular Science Monthly 



A Simple Tracing Method for Electrical 

 Draftsmen 



ATIME-SAVKK for t-loctrical drafts- 

 men is shown iK-rt'vvith. The idea 

 is to draw standard details on a paper, or 

 still better, on a tracing cloth template, 

 repeating each figure to each of the 

 standard scales used in the office. 



\\'hcn these figures occur in tracing 

 a drawing, the template is slipped under 

 the tracing cloth so as to bring the 

 proper figure, drawn to the proper scale, 

 into position, when it is traced direct, 

 saving the time necessary to make a 



Lightening Automobiles with 

 Aluminum 



Tlll'^ most pronounced tendency 

 connection with modern auton 



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BATTERIES 



ENCLOSED MOTOR 



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SERIES WOUND MOTOR 

 OR DYN. 



METERS 



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SHUNT WOUND MOTOR 

 OR OYN. 



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COMPOUND WOUND 

 MOTOR OR DYN. 



'Stock drawings or templates to slip under tracing 

 cloth as an aid in drawing in machine parts 



scale drawing of that particular symbol. 

 This idea may be extended as far as 

 profitable, as the templates can be made 

 up as a filler job. — Frank Har.\zim. 



A Table Mat That is Both Decorative 

 and Protective 



i.N ingenious device for l.ii)lc - lu.ils 



is an embroidcrc-d linen slip, in>ide 



1 which isplaci'd a sheet of while asbestos. 



A-' 



m 

 tomo- 



bile develo|)ment is the reduction of car 

 weight that has been made by all leading 

 manufacturers in their recent models. 

 One way of lightening the power-plant 

 is to use small cylinders and obtain the 

 power desired by increasing the piston 

 speed and, of course, the number of ex- 

 [)losions in a given time. The experi- 

 mental work done in connection with 

 high-speed motor design brought out 

 the desirability of using light 

 reciprocating parts. To attain 

 this end, aluminum-alloy pistons 

 were tried instead of cast-iron 

 and these have been so successful 

 that many new engines will be 

 equipped with pistons of the 

 lighter metal. Aluminum parts 

 weigh about one-third as much 

 as cast-iron ones of the same 

 size, so the reduction of recip- 

 rocating weight materially re- 

 duces vibration and makes higher 

 speeds possible. 



All of the higher grade engines 

 have always used aluminum 

 crank-cases, but it remained for 

 an ingenious designer to use 

 aluminum for his cylinder-block 

 casting in a iyi6 power-plant. 

 This engine is the nearest ap- 

 proach to the aluminum motor 

 that has ever been made, since 

 e\ery jiart that could be made of 

 that material has I)een con- 

 structed in some alloy of it. 



Of course, there are numerous 

 parts where it is not possible or 

 [jractical to use aluminum. The 

 crank-shaft, cam-shaft and con- 

 necting rods, for instance, must 

 be of steel and very excellent 

 metal at that. The wilvesand wrisl|>ins 

 must be of steel and the ll\-\vlieel ol slivl 

 or cast-iron, because this part must be 

 heavy to be efTective. In this engine, 

 even the cylinder-head casting is made of 

 aluminum, the valves seating on cast-iron 

 \alve seats, made solid in the casting 

 b\' the ingi-nioiis process of placing them 

 in till' molil and pouring the molten 

 mclal around them, when the c\liiidi'r- 

 head is cast. The valve-stem guides are 



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