310. Royal Astronojnical Society, 



The elements represent the Greenwich observation on the 20th of 

 February with errors of — 2"'3 in longitude and — 11"- in latitude. 



The observation at Berlin on Dec. 17 gives +8"'4 in longitude 

 and +24"-l in latitude. 



The period agrees exactly with that found by Plantamour, and 

 very nearly with the results of Le Jeune, Faye, &c.* 



June 14. — The following communications were read : — 



I. Some remarks on the Telescopic Appearance of the Moon, ac- 

 companying a Model and a Drawing of a Portion of her Surface, 

 By James Nasmyth, Esq. 



The model and drawing submitted to the Society by the author, 

 represent a portion of the moon's surface of 190 by 160 miles, situ- 

 ated in the upper part of her left limb as seen in an inverting tele- 

 scope, having in the centre the large crater marked in the Berlin 

 chart No. 29, and named " Maurolicu&s" 



The scale of the drawing is one- eighth of an inch to a mile. The 

 telescopes employed were two Newtonian reflectors, one of Sf inches 

 aperture, and 9 feet focal length, and the other of 12 inches aperture, 

 and 13 feet focal length, the powers employed being 240 and 360. 

 The author has, for the last four years, confined his attention almost 

 exclusively to the nature and structure of the lunar disc, and he se- 

 lected the portion above mentioned as a subject for a model by reasori 

 of its comprising in a small sjiace most of the chief features which 

 so remarkably distinguish her surface. 



The model was constructed with a view of illustrating the close 

 relationship which appears to exist between the structure of the lunar 

 surface and that of a considerable portion of the earth, in regard to 

 the similarity in the results of vast volcanic action. 



The author, in reference to the nature of the peculiarities of the 

 surface of the moon, first remarks on the vast size of the lunar cra- 

 ters as compared with those on the surface of the earth. Of these 

 there exist some of the enormous magnitude of 150 miles in diame- 

 ter, besides other circular formations, such as the " Mare Serenitatis," 

 and " Mare Crisium,"' which are from 200 to 300 miles in diameter, 

 and which evidently owe their form to volcanic action of prodigious 

 central energy. This enormous effect, compared with that of vol- 

 canic agency on the earth's surface, will appear less surprising when 

 w^e consider that the mass of the moon is scarcely the y^th part of 

 that of the earth, and that, consequently, the weight of the materials 

 acted on by the volcanic force is diminished very considerably com- 

 pared with bodies on the earth's surface : the probable want of atmo- 

 spheric resistance will also assist in accounting for the immensely 

 greater effects produced. The beautiful and almost perfectly circu- 

 lar form of the majority of the lunar craters may be due to the ab- 

 sence of wind or other disturbing causes, permitting the discharged 

 materials to perform the course due to the impulse comparatively free 

 from all impediment. 



There are several portions of the moon's surface which indicate 

 that considerable time has elapsed between the formation of one 



* See also our preceding volume, p. 519, and former reports of pro- 

 ceedings of the Astronomical Society in the present volume. — Edit. 



