378 THE POPULAR SCIENCE MONTHLY. 



cers have, however, influenced by what is said in English books, often 

 supposed that no royalty need be paid when Government authorizes 

 the use. Thus, a while ago, an army officer who contrived an improved 

 cartridge-box submitted it to the War Department, and the depart- 

 ment adopted it, but refused to pay the inventor. He sued in the 

 Court of Claims, which said that the case was to be treated as if Gov- 

 ernment had agreed to pay a reasonable price. More recently, when 

 Mr. James, the Postmaster of New York City, used a patented inven- 

 tion for canceling postage-stamps, with the result of saving to the 

 Government, through a term of years, some sixty thousand dollars, 

 the Circuit Court said that he must pay damages in the same light as 

 if he had been an infringer on his own account, and must obtain reim- 

 bursement from Congress as he might be able. Attorney-General 

 De\'ens gave an official opinion to the like effect. Upon the theory of 

 these decisions, if a patented invention is used in Government business 

 with the inventor's consent, the Court of Claims may award him com- 

 j)ensation upon an implied contract to pay ; or, if it is used against his 

 will, he may prosecute the officer as an individual, and the interest of 

 Government in the matter will be no defense. 



->- 



EECENT ADVANCES IN ELECTEIC LIGHTING.* 



By'W. h. peeece. 



ADVANCES have been made, not so much in electric lighting 

 , itself as in the popular favor with which it is regarded. The 



public is becoming more accustomed to its use, and is acquiring more 

 confidence in it. The result of trials during the last year or two 

 has been to make the defects of the electric light better known. It 

 has been taken out of the experimental stage, and brought within 

 reach of the practical stage. The principal fact Avhich has brought 

 the electric light to the front has been the substitution of machinery 

 for the direct conversion of mechanical energy into electricity for the 

 expensive batteries which were the only sources a few years ago. 

 Machines, working with high velocity, great steadiness, and uniform 

 pressure, have solved the problem of cheap electricity. The amount 

 of coal required to produce one horse-power has been reduced from 

 seven and eight pounds to three and even two pounds. The gas- 

 engine a very economical source of energy has been successfully 

 applied to electric lighting in many places. Such an engine has been 

 used at the docks in Newport, South Wales, to produce a light of 

 eleven times the power that the same gas would give if used directly. 



* Abstract of a lecture before the London Society of Arts. 



