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Show PHOTC CAPHIKG THE MOCN. aprelnl I'lnlrs ntnt Arpsntliis I'svd to Hi-rm Ni-aitlltr. ' Willi tho upiilleiitliiii of photography to nsaniioiny inucli iittontlou bus tint-nraiiy tint-nraiiy been given to lunar piiotora-poy. piiotora-poy. In JfM. less llinn o:io year alter I 'iiiiiierre'a illnovrry, I ir. John W. I'raper o'.itnlned the first phoiogrnpb of tlio liicici, but villi Hiuall nud Imperfect Im-perfect apparatus. Tito rxpusiiru time required wna twenty mliiutea. In ls '..'-'tlli '..'-'tlli n very great ndvnneo wna mado by ins o:i, Ur. Henry liraper, who usedn puwerrul retiecting teles opu of bla own construction. Tho imago of the moon ou bis i liotoginpha wna ahghtly less tl nn ono uud one bait lncbia In diameter. 'J en years later Pr. Lew la M. Ruth-' erford. of New York, secured many ex. qulsltrly aharp lunar phiilograpba, using a very different form of instrument, instru-ment, a thlrteen lniii refracting telescope tele-scope with a "photographic corrector" an aildltinniil lens, by menus of wbleU ills visual telescope could be converted Into n photographic one. Ity tho use of n method perfected by tho writer 111 I'.Hto, tho Yerka refractor refrac-tor la made avullnble for direct photo-Kinphy photo-Kinphy of tho moon, planets, atnr clusters clus-ters nnd so on. The method la extremely ex-tremely simple nml economlenl aud la applicable to nil visual telescopes. Instead In-stead of the ordlnnry blue aensltle pbotogrnphlc plntes, Isoehromutlc platea are used, which are very aei sl-tlre sl-tlre to yellow light. Mounted In the pinto holder cloo In front of the sensitive sensi-tive pinto la a lnrgc, brilliantly transparent trans-parent yellow color screen or ray filter. Thla excludes the out-of focus blue light, which would otherwise ilcairoy tho aharpnesa of the photograph, and nllnwa only the aharp yellow or visual Imago In reach the sensitive plate. With thla arrangement the great telescope tele-scope pliotou'mpha tlio moon with an expnsuro of less tlinu one aecond. flu account of tho alio nud length of the teleacopo and the elTecllvenesa of the color acrepn method, the resulting rieg. ntlvea allow amnller detnlls of the moon's aurfneo than linvo been photographed photo-graphed before. Hnrpor'a Mngnzlue. |