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Show lAuipi ftrtnnuu li.."t1loi. An Incandescent lamp, tho lumitlon of it IVincli army ollloer, h placid ut the end of n bnus tube, blackmed ou tho inside, with it mirror set In It at an might of ii dig,, so that It will retlut up ihruudli tho tubo the light of tho chttrlo lamp U low, which Is thrown ngtlnst tho walls of thu projoctlto or cannon which It Is desirable to examine Tho lamp und tube aro hi Id Inn ecu tml posltlou by n brus ring, which fits In tho center ot tho jrojeetlle, and through tho ring tho tubn can bo puho 1 by a twUtlng motion until tho lamp rmclies tho bottom, aud ewr jtart of tho Interior cjiimtiiwL A secondary battery, or n small hind dyuniuo, will furnlth tho current nccnry to run tlu lttup. ew xork Telegram, |