226 Royal Astronomical Society. 



131 books not bound or catalogued; and tbat 6 volumes were yet 

 to be delivered : that the Council had this day determined to com- 

 plete the deficient sets of the most valuable works, to rearrange the 

 library, and to prepare a new catalogue, uniting the books of the two 

 societies as early as possible. 



It was then moved by the Rev. R. Sheepshanks, seconded by Mr. 

 Drach, and resolved unanimously, that the warm thanks of the meet- 

 ing be given to Mr. Stratfoi'd, for the trouble which he had taken in 

 behalf of the Society, in carrying into effect the resolution of the 

 last meeting with regard to the Mathematical Society. 



Sir J. Herschel exhibited to the meeting a model of the surface of 

 the moon, constructed by Frau Hofriithinn Witte, a lady resident in 

 Hanover, from her own observations made with an achromatic tele- 

 scope by Fraunhofer, placed in a small observatory on the roof of her 

 dwelling-house, in that city. The model is composed of a mixture 

 of mastic and wax, forming a globe 1 2 inches 8y lines, Paris measure, 

 in diameter, on which the positions and general outlines of the 

 craters, and other remarkable features of the moon's surface, were 

 in the first instance laid down from the latitudes and longitudes 

 given by Messrs. Baer and Madler in their work entitled Der Mond, 

 and from their chart of the moon, and the modeling performed (with 

 the aid of a magnifying- glass) from the actual appearance of the 

 objects as presented in the telescope above mentioned. The globe 

 in question is the ten millionth part of the actual diameter of the 

 moon, in which proportion, therefore, the horizontal linear dimen- 

 sions of the several mountains, &c. are laid down. But, in respect 

 of the height, a double proportion is adopted, since otherwise the re- 

 lative heights would have been with difficulty distinguishable on so 

 small a model. Sir J. Herschel having explained the nature and 

 mode of construction of this admirable work (of which only one other 

 exists, now in the Royal Museum of Berlin — both being originals, 

 and attempts to multiply copies by taking plaster casts having 

 hitherto failed), pointed out several of the principal craters, and ex- 

 plained the nomenclature adopted by Messrs. Baer and Madler in 

 their work referred to, in describing the several characteristic pecu- 

 liarities of the moon's surface. The model was, on the breaking up 

 of the meeting, submitted to the closer inspection of the members. 



December 12. — On a Direct Method of determining the Distance 

 of a Comet by Three Observations. By J. J. Waterston, Esq. 



The following is the author's explanation of his method : — 



" It is well known that three observations of a comet afford suffi- 

 cient data for computing its distance from the earth independently 

 of any assumption as to the orbit in which it moves. The formula 

 is, I believe, originally due to Lambert, and appears in the works of 

 the principal mathematicians who have given analytical solutions of 

 the problem by the differential method. It is unfortunate that the 

 nature of the equation does not admit of much precision in the re- 

 sults of the calculation, which are consequently apt to be greatly 

 affected by small errors of observation. The disturbing power of 

 these unavoidable inaccuracies varies much according to the condi- 



