Popular science monthly . Mounting of the seventy-two-inch reflector of the Dominion Observatory of Canada, to beinstalled at Victoria, British Columbia. The principles of construction are the same what-ever the size of the instrument, but the great weight of a large reflector makes the engineeringproblem a difficult one. The weight of the mirror cell with the mirror is six tons. The polar axiswhich is bolted to the pierheads, weighs ten tons. The skeleton tube weighs two tons. Thedotted lines represent the path of the rays of light. The polar axis must be set parallel to theaxis of rotation o
Popular science monthly . Mounting of the seventy-two-inch reflector of the Dominion Observatory of Canada, to beinstalled at Victoria, British Columbia. The principles of construction are the same what-ever the size of the instrument, but the great weight of a large reflector makes the engineeringproblem a difficult one. The weight of the mirror cell with the mirror is six tons. The polar axiswhich is bolted to the pierheads, weighs ten tons. The skeleton tube weighs two tons. Thedotted lines represent the path of the rays of light. The polar axis must be set parallel to theaxis of rotation of tiic earth. In the latitude of Victoria, it makes an angle of more than forty-eight degrees with the horizon Popular Science Mo)if/il!/ mi. Above: The build-ing complete, up tothe covering of thedome. This is fur-nished with a sys-tem of shutterswhich with thedouble wall permitan even tempera-ture to be main-tained in the interiorof the building Above: The ironframework of thewalls. Horizontalribs are attachedin pairs both to theouter and inneredges of the up-right beams, thusforming a doublewall with an inter-mediate air-space The permanentconcrete pier at Vic-toria. The ends ofthe polar axis aresupported on steelcastings which arebolted to theheads of the piers having already been captured. It is alsoextremely valuable for spectroscopic long exposure is required even with thegreat forty-inch Yerkes refractor to olilainthe spectrogram of a star of the fourthmagnitude. This is much reduced at by using the short focus sixty-inchmirror, not only on account of the largersize, but also because the loss of lightcaused by reflection is much less than that suffered by a ray of light in passing throughthe thick l
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectscience, bookyear1872
