Page:Philosophical Transactions - Volume 001.djvu/42

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that it is always to rise before the Sun, and that we may again see it better, when it shall rise betimes, towards the end of May, and in the beginning of June, if the clearness of the Day-break hinder us not; he thought it worth the while to try, whether the truth of this Ephemerides could be proved.

He affirms then, that the Line described by this Star resembles hitherto a Great Circle, as it is found in all other Comets in the midst of their Course. He finds the said Circle inclined to the Ecliptique about 26.d. 30′. and the Nodes, where it cuts it, towards the beginning of Gemini and Sagittary: that it declines from the Equator about 26.d. and cuts it towards the 11.d. and consequently, that its greatest Latitude hath been towards Pisces, where it must have been March 24. and its greatest Declination, towards the 25. d., of the Equator, where it was to have been April 11.

He puts it in its Perigee March 27. about three of the Clock in the Afternoon, when it was about the 15. degrees of Pisces, a little more Westerly then Marchab, or the Wing of Pegasus, and that it was to be in Conjunction with the Sun, April 9. Where yet he noteth, that according to another Calculation, the Perigee was March 27. more towards Night, so that the Comet advances a little more towards the East, and retards towards the West; which not being very sensible in the first days, differs more about the end, and in the beginning; which he leaves to Observation.

He calculateth, that the greatest Motion it could make in one day, hath been 4. d. and 8′. or 9′; in one hour, about 10′. and 25″. so that its Diurnal Motion is to its left distance from the Earth a little more than as 1. to 14. and its Hourly Motion, as 1. to 330.

He wonders, that it hath not been seen sooner; the first Observations that he hath seen, but made by others, being of March 17. Whereas he finds, that it might have been seen since January, at least in the Months of February and March, when it rose at 2 of the Clock and before: because it is very likely, that, considering its bigness and brightness, when it was towards its Perigee, it was visible, since that towards the end of February it was not three times as much remote from the Earth, than when it was in its Perigee, and that towards the end of January it was not five times as much.