Show have catalogue of stars at cambridge mass there now ex ei ista the most extensive and valuable collection of stellar photographs in the world numbering over and or more of them have been secured at harvard university observatory at arequipa peru at an elevation of feet the number of stars stara revealed on the different plates depends of course on the density of the part of the sky being pho to graphed and on the length of the exposure the longer the exposure the more stars provided the light of the sky does not fog the plate on one plate alone namely the region about eta Carl Car inae nae elars have been actually counted |