416 



Popular Science Monthly 



the strength of the emanation in the sup- 

 phed air at its proper value. For this pur- 

 pose he uses an electric instrument which 

 he reads through sighting apertures. The 

 instrument is operat- 

 ed by the electrically 

 charged emanation, so 

 that the degree of the 

 activity is indicated 

 by the amount the in- 

 strument is affected. 

 The instrument 

 shown in the illustra- 

 tions — an electromet- 

 er, it is sometimes 

 called — can measure 

 the activity in the air 

 to a high degree of 

 accuracy. 



Curing rheumatic 

 ailments by the water 

 of the now famous 

 European springs is a 

 treatment which has 

 come down through 



many ages. Unknown to the travelers, the 

 success of this treatment was principally 

 due to the action of the radium salts which 

 were dissolved in the springs. When this 

 fact was discovered, the idea immediately 

 suggested itself of using ordinary liquids in 

 which the emanations could be dissolved. 

 The liquids could be charged at stations 

 distributed all over the world, and the 

 treatment made available to almost every- 

 body. This is now actually being done 

 and small iron tanks containing the 

 active liquids can be ordered by mail 

 in Europe. 



teries to a service station for recharging. 

 But a new gas rectifier has been placed 

 on the market which will recharge even 

 as few as three batteries inexpensively. 

 It consists princi- 

 pally of a small bulb 

 filled with nitrogen 

 gas and contain- 

 ing electrodes of 

 tungsten and of 

 graphite. This bulb 

 screws into a socket 

 on a panel of the ap- 

 paratus like the bulb 

 of an ordinary elec- 

 tric light. The com- 

 plete apparatus is 

 connected with the 

 alternating supply 

 main, two leads on 

 the other side of it 

 are connected with 

 the batteries, and a 

 switch turns it on. 



The patient, charged to a high voltage, 

 breathes in the electrically charged air 



A Remarkable Rectifier for 

 Charging Batteries on 

 Alternating Current 



EVERYBODY knows that 

 used storage batteries can be 

 recharged only on direct current. 

 The automobile owner 

 whose individual garage is 

 supplied with 



A Burglar-Alarm for Foiling 

 the Automobile Thief 



A PROFESSIONAL automobile thief 

 can break through locks and guards 

 and get almost any automobile started. 

 But one thing he wouldn't count on would 

 be a burglar-alarm clanging with him as 

 he dashes down the street. Such an alarm 

 for announcing his profession to the 

 policemen that he would pass has 

 been invented by William Con- 

 noly, of New York city. An 

 electric circuit-closer is mount- 

 ed directly under the driver's 

 seat and the least pres- 

 sure on it will close a 

 circuit running to a large 

 bell. All the parts are 

 locked in places that 

 cannot be easily 

 reached, and 

 the thief will 

 be greeted with 

 the clanging 

 alarm' as soon 

 as he takes his 

 seat. 



Pressure on the 

 seat closes an alarm 

 circuit underneath 

 so that a bell clangs 

 loudly as the thief 

 vainly tries to get 

 away undetected 



