7°9 18 3 48 59 O 95 50 Feb. 7, April 14, June 20, Aug. 25, A. Oct. 30 February 20, July 30 K. Jan. 28, April 9, June 20, Aug. 31, A. B. ... Minima of the Short Period Variable Stars during 1859 in Algol. Maximum 2-3; Minimum 40. Whole variation completed in seven hours. Principal Minimum (4°3); First Max. (3'4) about 3d 2h after. Second Min. (3.8) about 6a 9h after.; Second Max. (3'4) about 9d 10h after. The corrections to be applied to the observed times of minima of the short-period variables, before comparing with the ephemeris may be found by the formulæ on page 27 of vol. xvii. of the Monthly Notices. With very few exceptions, the same elements have been employed in preparing this as in the last year's ephemeris. When no authority is stated, the times of maxima must only be regarded as indications as to when a search will prove most beneficial for the determination of the elements of variation of such star. If invisible, a mere record of such being the case will, by contradicting the assumed elements, remove an erroneous prediction from the next ephemeris, and thereby possess great interest and value. For the short-period variables (all of which except a Tauri are from Prof. Argelander's elements), those minima only are tabulated which occur when the sun is considerably below, and the star at least ten degrees above, the horizon. I have again to acknowledge my obligation to Mr. Baxendell for having obligingly communicated the ephemerides of a Fauri, 13 Lyra, R and S Herculis, based upon elements derived from his own observations. The unavoidable delay in the preparation of this little annual contribution is a matter of much regret, but one which, I am happy to say, is not likely to happen again. Change of residence, and other pressing interruptions, all conspired to derange my plans, and throw me behind in their execution. The variable stars are, however, marked out as special objects. · of observation and investigation in Dr. Lee's Observatory, and I shall therefore hope to have the ephemeris for 1860 in print before the close of the present year. Hartwell Observatory, April 11, 1859. Results of the Observations of Small Planets, made at the Royal Observatory, Greenwich, in the month of March, 1859. (Communicated by the Astronomer Royal.) On the Secular Variation of the Eccentricity and Inclination of the Moon's Orbit. By Professor Adams. "In a memoir read before the Royal Society in June, 1853, I showed that the secular variation of the moon's mean motion is given by means of the equation in which the coefficient of m4 is totally different from that in Plana's result. "I have since carried the approximation to the seventh order in m, and find that 2 This reduces the coefficient of (1), in the expression for the 100 acceleration to 57, only about one-half of the value hitherto received. M. Delaunay has recently verified my coefficient of m; and he informs me that he shall very soon have carried the approximation to the eighth order in m, and included the terms depending on e2 and y2. "In my memoir above referred to I mentioned that other elements of the moon's orbit suffer secular changes which had been overlooked. "I find the following expressions for the secular variation of the eccentricity and inclination of the moon's orbit, adopting. Plana's definitions of e and :— "I am engaged in carrying on the approximation to the de value of to the same extent as I have done in the case of dy dt' dt and in finding the part of the secular variation of the mean motion which depends on e2 and y2. These terms, however, can only very slightly affect the numerical value of the secular acceleration." |