OBSERVATIONS ON THE COMET OF MARCH 4TH, 1847. Made at Cambridge Observatory. Long. 4h 44m 32". Corrected for refraction, and referred to the Mean Equinox of Jan. 1st, 1847. "March 4th. The comet was first seen at 7 o'clock, in close proximity to a star of the 10, 11 magnitude; in brightness it appears to be but just beyond the limit of unassisted vision. It has no visible nucleus, and but slight condensation of light towards its centre. Faint traces of a tail are suspected in a direction nearly opposite to the sun. The observations this evening are made with the annular micrometer. "March 5th. From this date up to the 24th, the spider-line micrometer was employed, the field being illuminated with red light. "March 6th. The comet is brighter than heretofore, showing a tail of 20 in length, of a conical outline, its axis being directed towards the sun. The head of the comet is very irregular, its light is somewhat concentrated, but there is no well-defined nucleus, which circumstance in some degree affects the accuracy of the observations. "March 8th. To-night, for the first time, the comet is visible to the naked eye, as a star of the fifth or sixth magnitude. The angle of position of the tail is n. f. 76° 30'; consequently it is not exactly in a direction opposite to the sun. The estimated diameter of the light surrounding the head was four or five minutes of arc. "March 12th. In the comet-seeker the tail may be traced two or three degrees. Angle of position of its axis is 81° n. f. "March 15th. The rough and irregular outline of this comet reminds one of the figures of Hevelius. Length of the tail four or five degrees. "March 24th. The altitude of the comet at this observation was three degrees. The place given is derived from a single passage over the annular micrometer, and is therefore liable to some uncertainty; it however agreed nearly with the result from instrumental readings. "The following elements have been computed from the observations given above. By Professor Peirce, from the observations on March 4th, 5th, and 6th. 1847, Per. passage, March 31.907, Greenwich M. S. T. "By G. P Bond, from places of March 5th, 12th, and 19th, account being taken of the small corrections. 1847, Per. passage, March 30.3369, Greenwich M. S. T. "The places computed from the latter orbit require the following Mr. William C. Bond communicated a second series of moon culminations observed at the Cambridge Observatory. "The observations now presented to the Academy were made at the first station occupied as an Observatory in Cambridge. Lat. 42° 22′ 22′′. Long. 4h 44m 30". The Transit Instrument has an objectglass of 2 inches aperture, and 46 inches focus. The clock error has been determined solely by means of the standard stars of the Nautical Almanac. The southern meridian mark of this station is situated on Blue Hill, in Canton; it is placed on a massive and conspicuous stone tower, erected for the purpose, 58,520 feet south of the transit instrument, and within a short distance of one of the principal stations of the State and United States Surveys. MOON CULMINATIONS, Observed at Cambridge, corrected for Collimation, Level, and Azimuthal Deviation of the Transit Instrument, and for Clock Rate and Error on Sidereal Time. Lat. 42° 22' 22". Lon. West of Greenwich, 4 h. 44 m. 30s. 12 30 43.64 1 Leonis 236 Virginis 12 33 35.14 34.33 -0.81 "" 12 46 03.42 03.53+0.11| * B is the initial of William C. Bond; W, that of William C. Bond, Jr. |