Popular Science Monthly 



687 



Open Your Mouth and Let the Doctor 

 Flashlight Its Interior 



AN interesting little de- 

 L vice recently invented 

 for the convenience of physi- 

 cians and dentists, is an 

 automatic mouth in- 

 specting lamp. 



A small electric bulb 

 is fitted into a short 

 tube which is itself 

 hinged to a larger cylin- 

 der containing the stan- 

 dard flashlight batteries. 

 A wooden tongue-de- 

 presser is attached to 

 the tube. When the 

 surgeon presses down 

 your tongue with this, 

 the tube is swung slight- 

 ly on its hinge. This ac- 

 tion produces the light. 



When 

 tongue 

 circuit 



started, this system supplies practically a 

 constant circulation, so that when the en- 

 gine is working under a heavier load than 

 usual, and therefore requires a 

 greater circulation, it does not get 

 it. This lack causes over- 

 heating. 



This deficiency is 

 overcome by the simple 

 pump shown below. 

 It consists of a screw- 

 like blade working in a 

 short barrel inserted in 

 the regular Ford water 

 line between the radi- 

 ator and the engine. 

 The blade is revolved by 

 means of a small belt 

 and pulley driven by 

 the big radiator fen- 

 shaft. The faster the 

 engine revolves the more 

 wateriscirculated. 



the surgeon depresses your 

 , the action closes an electric 

 and illuminates your mouth 



Preventing the Ford Engine from Over- 

 heating—A Simple Pump Does It 



THE engine of the Ford car often over- 

 heats in the hot weather when driving 

 fast or work- 

 ing under a 

 hard pull be- 

 cause of the 

 thermo-sy- 

 phon water 

 cooling sys- 

 tem e m - 

 ployed. In 

 this system 

 the water cir- 

 culates from 

 the radiator 

 to the cylin- 

 ders and back 

 again in ac- 

 cordance with 

 the natural 

 law which 

 causes hot 

 water to rise 

 to the top 

 while cold 

 water drops 

 to the bottom. 

 After the en- 

 gine is once 



The water circulates continuously from the radiator to 

 the cylinders and back, forced at times by a screw- 

 like blade which is revolved by a belt and pulley 



Lucky and Unlucky Telephone Num- 

 bers — In Japan They Affect Your Bill 



OUR only unlucky number is 13. In 

 Japan they have two unlucky num- 

 bers — 42 and 

 49. Nobody 

 wants either 

 of these num- 

 bers for a tele- 

 phone call, 

 simply be- 

 cause the for- 

 mer is pro- 

 n o u n c e d 

 "shini, "which 

 means "to 

 - die" and the 

 latter is pro- 

 n o u n c e d 

 ' ' s h i ku , ' ' 

 which means 

 "death." The 

 luckiest tel- 

 phone num- 

 ber in the esti- 

 mation of the 

 J a pa n ese 

 business man 

 iseight, which 

 suggests pros- 

 perity. 



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 Science Monthly is at your disposal. Write to the editor if you think he can help you. 



