American horological journal, devoted to practical horology (1869)
Miller, George B · New York, G. B. Miller · leaf 242
equatorial mounted telescopes,and also some European ones, are made onthis principle. No other plan yet devisedappears to give more satisfactory results inproducing that accurate rotary motion sonecessary in certain astronomical instru-ments. A description of this invention hasalready appeared in… … by the angular point A. This pendulum isconstructed with a view of diminishing thelength of the common pendulum, but at thesame time to maintain, or even increase, thetimes of vibration. In this pendulum thetime of vibration depends on the length ofthe legs, and on the angle contained betweenthem…
Clocks and watches
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