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which h ath since been eredted for the same Purpose and upon the like Principles, though it is fomewhat different in its Conftru&ion, for a Reafon you will meet with presently.
Mr. Molyneux's Apparatus was compleated and fitted for observing about the End of November 172.5, and on the third Day of ‘December following, the bright Star in the Head of 'Draco (marked y by Boyer) was for the first Time obferved, as it pasted near the Zenith, and its Situation carefully taken with the Instrument. The like Observations were made on the fth, nth, and nth Days of the fame Month, and there appearing no material Difference in the Place of the Star, a farther Repetition of them at this Seafon seemed needlefs, it being a Part of the Year, wherein no sensible Alteration of Parallax in this Star could foon be expe<Sted. It was chiefly therefore Curiosity that tempted me (being then at Kew, where the Instrument was fixed) to prepare for observing the Star on December 17th, when having adjusted the Instrument as usual, I perceived that it pasted a little more Southerly this Day than when it was obferved before. Not sufpe&ing any other Cause of this Appearance, we first concluded, that it was owing to the Uncertainty of the Observations, and that either this or the foregoing were not fo exadt as we had before supposed ; for which Reafon we purposed to repeat the Observation again, in order to determine from whence this Difference proceeded ; and upon doing it on December xoth, I found that the Star pasted still more Southerly than in the former Observations. This sensible Alteration the. more surprized us, in that it was the contrary
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way from what it would have been, had it proceeded from an annual Parallax of the Star : But being now pretty well satisfied, that it could not be entirely owing to the want of Exadtnefs in the Observations ; and having no Notion of any thing else, that could cause such an apparent Motion as this in the Star; we began to think that fome Change in the Materials, &c. of the Instrument itself, might have occasioned it. Under these Apprehensions we remained fome time, but being at length fully convinced, by several Trials, of the great Exactness of the Instrument, and finding by the gradual Increase of the Stars Distance from the Pole, that there must be Some regular Caufe that produced it ; we took care to examine nicely, at the Time cf each Observation, how much it was: and about the Beginning of March 17x6, the Star was found to be zo" more Southerly than at the Time of the first Observation. It now indeed seemed to have arrived at its utmost Limit Southward, because in several Trials made a-bout this Time, no sensible Difference was observed in its Situation. By the Middle of April it appeared to be returning back again towards the North ; and about the Beginning of June, it pasted at the same Distance from the Zenith as it had done in 'December, when it was first: observed.
From the quick Alteration of this Star’s Declina-nation about this Time (it increasing a Second in three Days ) it was concluded, that it would now proceed North ward, as it before had gone Southward of its prefent Situation ; and it happened as was conjectured : for the Star continued to move Northward rill September following, when it again became stationary,