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 department 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 Government had agreed to pay a reasonable price. More recently, when Mr. James, the Postmaster of New York City, used a patented invention 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 reimbursement from Congress as he might be able. Attorney-General Devens 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 compensation 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.
|RECENT ADVANCES IN ELECTRIC LIGHTING.|
By W. H. PREECE.
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 which 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.