The Royal observatory, Greenwich. A glance at its history and work (1900)
Maunder, E. Walter (Edward Walter), 1851-1928 · London, The Religious tract society · leaf 294
brings into action a second wheel, whichaccelerates or retards the driving of the clock, as thecase may be. The total motion, therefore, is mostbeautifully even. But even this is not quite sufficient, especially asthe plates for the great chart have to be exposedfor at least forty minutes. Rigidly… … THE ASTROGRAPHIC TELESCOPE. {Reproducedfrom Engineering by permission.) piece are fixed two pairs of cross spider lines,commonly called wires, and a bright star, as near as 292 THE ROYAL OBSERVATORY possible to the centre of the field to be photographed,is brought to the junction of two wires.…
Royal Greenwich Observatory · Astronomy
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