An Account of an Observation of an Eclipse of the Moon, Observed at Moscua in Russia, on April 5. 1688. Compared with the Same Observed at Lipsick; whereby the Longitude of the former Place is Ascertained: Together with the Latitude of Several Principal Places in the Empire of Russia

An Account of an Observation of an Eclipse of the Moon, observed at Moscua in Russia, on April 5, 1688, compared with the same observed at Lipsick; whereby the Longitude of the former Place is ascertained: Together with the Latitude of several principal Places in the Empire of Russia. The Royal Society being desirous to contribute what they may to the rectifying of Geography, and determining the Longitudes of Places, amongst others did recommend the procuring an Eclipse to be observed at Moscua, to an eminent Merchant trading there; at whose instance one Mr. Timmerman, a Mathematician, residing on the place, returned the following account. April 5, 1688. half a quarter of an hour after seven in the Evening, the Moon arose clear, but of a deep red colour without any sign of Eclipse: at $7^h \frac{1}{2}$ the Moon went into a thick Cloud, but was again clear at $7^h 38^m$ when the under-side of the Body of the Moon was begun to be obscured, in a clear Sky; she being then in the $25^{th}$ degree of Libra, and $6^\circ \frac{1}{2}$ above the Horizon. (Suppose the Center.) At $9^h$ the whole under-side of the Moon was eclipsed, and about 8 minutes after nine, it was at the height, or rather seemed to decrease. At $9^h \frac{1}{2}$ there was still a third part of the Moon Eclipsed. (Suppose of her Circumference.) About ten it decreased apace, and at $10^h \frac{1}{2}$ there was but little to be seen: At $10^h 45'$ it was certainly ended, the Moon being then about $22^\circ$ high. Thus far the Observer. The duration of this Eclipse is here made from $7^h 38'$ to about $10^h 45'$, which agrees within 8 or 10 minutes with our Tables, that never err sensibly in the continuance of Eclipses; and so much ought to be allowed to an Observer not sufficiently instructed to distinguish the Penumbra from the true shadow, though a small Telescope lescope were used in this Observation, as we are since informed. Let us conclude then, That the end was at $7^{h}40'$ at Moscua. We do not find that this Eclipse was observed at London, and it was in probability cloudy, and otherwise only the latter part thereof would have been visible: However this defect is in good part supplied by an Observation thereof made at Lipstick, by Mr. Gottfrid Kirck, and published in his Ephemerides for the Year 1689, where the end is determined at $8^{h}54'$ P.M. Hence Moscua will be $1^{h}46'$ to the Eastwards of Lipstick; and the difference of Meridians between London and Lipstick being already determined 49 min. it will follow that Moscua is $2^{h}35'$ to the East of London, or $38^{\circ}45'$ of Longitude, which from other Accounts we find to be very near that of the City of Aleppo in Syria. By the same Hand we have procured the Latitudes of the following Places, observed, as 'tis said, with a large Quadrant. | Place | Latitude | |-----------|----------| | Moscua | 55° 34' | | Tereflaw | 57° 44' | | Vologda | 59° 19' | | Voftak | 61° 15' | | Arkangel | 64° 30' |