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 251
circling the drum. If, however, theneedle moves, then the spot of light travels up ordown, as the case may be. 248 THE ROYAL OBSERVATORY Now, if we look at one of these sheets of photo-graphic paper after it has been taken from the drum,we shall see that the north pole of the magnet hasmoved a… … MAGNETIC PAVILION—INTERIOR. {From a photograph by Mr. Lacey.) of this daily swing is but small, but it is greater insummer than in winter, and it varies also from yearto year. Besides this daily swing, there occasionally happenwhat are called magnetic storms ; great convulsivetwitchings of the…
Royal Greenwich Observatory · Astronomy
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