Jones, H. Spencer (Harold Spencer), 1890- · London E. Arnold & co. · leaf 206
f a distant fixed object is available on whichthe instrument can be pointed, the position of this objectrelative to the centre wire is observed and the telescope is ASTRONOMICAL INSTRUMENTS 173 then reversed on its axes and again pointed to the same object.If the centre wire points in the same… … Fig. 61.—Three-inch Transit Instrument. is not available, a collimating telescope can be used. This isan auxiliary telescope, in the focus of which is placed twocross wires. The telescope is firmly mounted in the meridianwith its object-glass towards the transit instrument, so thatwhen the latter…
Astronomy
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