The Dictionary Of Photography

A True Historic Record Of The Art & Practice Of Photography 100 Years Ago.

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Astronomical Photography
bench should ordinarily be a rough, heavy table kept out ot doors, a recess in the bench and thumbscrew for each foot being sufficient; and care should be taken that when the stand is in its place the pillar is vertical. A position b is now found on the meridian line b c, where a line drawn from the centre of motion of the altitude axis A will form at b the angle abc equal to the
Fig. 10.
latitude of the place. A Londoner would therefore make the angle abc equal 510 30', and a worker in Edinburgh would make it equal 560. A cord is now attached to the telescope at the object glass and passed through the hole b, this cord being kept conveniently tense by a weight d, which weight should not be so heavy as to interfere with the free control of the telescope by the observer. The object having been found, the cord is clamped at b, and the object can now be followed by so moving