A friend in Pennsylvania writes: “Please give us a description of the transit of Venus, in THE CHAUTAUQUAN for January.” We answer with the following: At a meeting of the New York Academy of Sciences, at No. 12 West Thirty-first street, on the evening of December 13, Professor J. K. Rees, of Columbia College, gave the result of his observations of the transit of Venus, made at the college observatory. A large audience was present and listened attentively to the lecturer’s presentation of facts. “I will only detain the Academy a few moments,” said the Professor, “in presenting the main points in the observations made at Columbia College on December 6. Most of the figures I will leave out. The station occupied was the roof of the unfinished observatory of the college. The telescope was placed in the southwest corner of the roof. This roof is extraordinarily strong and solid, the beams being of iron, twelve inches in depth. Solid brick arches spring from beam to beam. The height of the roof from the street is about one hundred and ten feet. The walls supporting the roof are four feet thick. An unobstructed view was had of the whole transit. The position of the instrument was only a few feet from the old observatory, so that we may take the longitude and latitude of our instrument from the American ephemeris— Latitude, +40° 45′ 23″.1. Longitude:—From Washington, -0h. 12m. 18.40s. Longitude:—From Greenwich, +4h. 55m. 53.69s. “The timepieces used were a mean time chronometer, No. 1,853, made by Parkinson & Frodsham, of London, England, and a sidereal chronometer, No. 1,564, made by Negus & Co., of New York City. The instrument used in the observations was an equatorially mounted refractor by Alvan Clark & Sons. Aperture 5.09 inches; focal length of object glass, 74.3 inches. The magnifying powers used were 48 on the first contact, 165 on the second and third contacts, and 95 on the fourth contact. The telescope was moved by clockwork, supplied with a Bond spring governor. In making chronometer comparisons the sidereal chronometer was left at the college and the mean time chronometer was carried to the instruments on which signals were to be received. The sidereal chronometer has the hours graduated to XII.” Professor Rees had prepared, but omitted to give, an elaborate system of chronometer comparisons with the Western Union time signals and the Washington time signals. The object of the comparisons was to obtain the exact error of the chronometers used at the time of the observations. The Western Union time signals sound the local mean time at the City Hall of New York city. The longitude of the City Hall from Washington is 12m. 10.47s. Mr. Hamblet, in charge of the Western Union time system, gives the errors of the Western Union time signals as 1.11s. fast on December 5, noon; 1.35s. fast December 6, noon. The professor also omitted a table of observations and the times taken down at the instant by each of four recorders.