914 



Popular Science Monthly 



For the antenna and ground for his wireless 

 the lineman uses a pole with metal end- 

 caps which are connected with the receivers 



Detecting Defective Insulators 

 While Standing on the Ground 



LINEMEN usually climb transmission 

 vtowers to find defective insulators. 

 T. F. Johnson, of Geor- 

 gia, has a device which 

 will detect leaking 

 insulators without the 

 tower. 



The invention em- 

 ploys the same type of 

 instruments that are 

 used in wireless tele- 

 phony. In the trans- 

 mission of high tension 

 alternating current, 

 when electricity breaks 

 through an insulator, 

 little wireless waves are 

 sent off. The inspector, 

 therefore, simply car- 

 ries a wireless receiving 

 set with him. A de- 

 cided buzzing in his re- ^^ the match safe 

 ceivers is a sure sign of position a match is 

 trouble in the wires. glass cover and res 



We Use Eighteen Times as Much 

 Light as Did Our Grandfathers 



DR. WALTER CLARK, of Philadelphia, 

 has recently made some interesting 

 investigations to find out how the old- 

 time lighting conditions in his city compare 

 with those of to-day. He has discovered 

 that until as late as 1855, only flickering 

 sperm oil and candles were in use. Not 

 until the following decade did the "highly 

 improved" kerosene lamp appear. Gas 

 did not come out until the period between 

 1865 and 1875. And then only the wealthy 

 could use it. It sold at $2.50 per thousand 

 cubic feet ! The efficient Welsbach mantle 

 came out ten years later, revolutionizing 

 artificial illumination. The present era 

 began in 1895, when gas and' electricity 

 came into general use — gas selling at $1.00 

 per thousand cubic feet and electricity at 

 ten cents per kilowatt-hour. Since this 

 time the gas mantle and the electric fila- 

 ment have seen vast improvements, so 

 that to-day the average family is obtaining 

 about eighteen times as much light as the 

 people of half a century ago had, though 

 they pay only about three-quarters as much 

 for it as their grandfathers did for the dim 

 lights of other days. 



Matches? Take One At a Time, 

 If You Please 



THIS counter match safe is a 

 conserver of matches as well 

 as a dispenser. It is so 

 arranged that not more 

 than one match is de- 

 livered at a time unless 

 . the safe is unlocked for 

 the purpose. A small 

 hook at each side of the 

 carrier grasps one 

 match, which is lifted 

 when the operator rais- 

 es the box from its 

 normal position and 

 lets it fall back into 

 place. A small projec- 

 tion on the standard 

 dislodges the match 

 from its holder as it 

 rises above the rear 

 part of the glass cover. 

 The match rolls down 



is raised to its highest the slo P™« S laSS an £ 

 dropped down on the rests within easy reach 

 ts within easy reach of the customer. 



