Show Making a Light Without Heat The most wasteful the least efficient of all widelyused electrical devices Is the Incandcpccnt lamp Of all the power used In producing tho sovlng filament In the Edison bulb more than 91 per cent la 1 absolutely ab-solutely wasted scarcely 2 per cent appearing ap-pearing In light This 3 per cent efficiency of tho Incandeucent lamp compares vcrjl favorably Indeed with the iO per cent efficiency ef-ficiency of tho gasoline engine tho 22 percent per-cent efficiency of the marine engine and the 0 per rent efficiency of lie dynamo The waste of power In the Incandescent lamp If known I to bo duo largely l to the conversion of a considerable part of tho electricity used Into usolw hoat I was therefore necessary in produvo a cool light that Is a light In which the energy vau convfrtnd wholly or largely Into light rays and not Into hilt rays Mr Cooper Hewitt turned his attention to the gases Vhj could not seine Incandescent gas be made to yield the muchdesired light without with-out heat Thla was the germ of his Idea lIt took up experiment with mercury confined In a tuba from which tho air had S been exhausted Ho discovered that when once the high reslHtiuiPii of the cold mercury was overcome over-come a very much less powerful current foiindo ready passage and produced a very brilliant light 1 the Klow of tho mercury vapor This Mr Hewitt says wan tho crucial point the genesis of his three In vuntlons for all ot them arc applications of the mercury arcSny Stannard Baker In June McClure I |