26 



Your Feet Are Wiped When You 

 Enter Bohemian Bakeries 



IT is an old custom in Bohemian baker- 

 ies to wipe the boots of visitors as 

 they enter. There is a good deal of 

 wiping these days ; for the government 

 and city officials inspect the bakeries at 

 very frequent intervals in order to see 

 that the regulations regarding the 

 amount of flour used in bread are car- 

 ried out. 



The picture shows Dr. K. Gross, the 

 burgomaster of Prague and representa- 

 tives of the city council, entering one of 

 the bakeries" of the city. The burgomas- 

 ter is the man whose boots are being 

 wiped. 



How Range Finders Find the Range 



ONE of the most interesting facts 

 brought out in Germany's subma- 

 rine campaign against British commerce 

 was the accuracy with which the British 

 guns were trained upon occasional indis- 

 creet periscopes. 



The periscope tube is small, and an 

 especially difficult target at long range, 

 vet on a few occasions — occasions 



Popular Science Monthly 



which were so recurrent that the ac- 

 curacy could not be attributed to accident 

 — British guns have demolished peri- 

 scopes, thereby rendering the submersi- 

 ble helpless — an easy prey when she 

 came to the surface. 



Nor can this remarkable accuracy be 

 attributed entirely to the correctness of 

 the gim design. The fact of the matter 

 is that the British method of range-find- 

 ing, aside from being one of the most 

 interesting, is one of the most accurate 

 in the world. 



Whether the enemy appears in the 

 form of a glinting periscope on the wa- 

 ter, a black dot, or a ship on the horizon, 

 the method of range-finding is funda- 

 mentally the same. A range-finder works 

 on the same principle as that by which 

 we can estimate a distance with our 

 eyes. Lines drawn from our eyes to the 

 object form sides of an angle. The size 

 of this angle determines the distance. 

 Unconsciously and automatically we 

 reckon distances by the complicated proc- 

 ess known as triangulation. 



What we estimate roughly with our 

 eyes, range finders determine accurately 



The workman is not performing an act of homage. He is simply dusting off the shoes 



of the Burgomaster of Prague. It is an old Bohemian custom that the boots of all 



visitors to bakeries must be so wiped 



