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Word: focal (lookup in dictionary) (lookup stats)
Dates: during 1900-1909
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Usage:

...tube 21 feet long with a 60-inch aperture is being made and much of the old clock work and appliances will be changed for new ones operated by electricity. The reflecting lens is about 6 inches thick and weighs, with its cell, about a ton. The focal length is 28 1-2 feet. This gives an image upon a scale of 6 inches for a degree. The whole instrument will be covered by a moveable wooden shelter connected with a frame building, the upper floor of which is the observing room, the lower floor the silvering room. This telescope...

Author: NO WRITER ATTRIBUTED | Title: New Telescope at the Observatory. | 11/3/1904 | See Source »

...mirrors will be sent first for experimental purposes previous to setting up the whole instrument. An open space in the eastern part of the Observatory grounds near Bond street has been chosen as the site for the telescope. On account of its great height, about 27 feet in focal length, no dome will be erected...

Author: NO WRITER ATTRIBUTED | Title: New Telescope for the Observatory. | 10/3/1904 | See Source »

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