Page:Popular Science Monthly Volume 91.djvu/930

This page needs to be proofread.


��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.

��� �