48 



ASTEONOMIOAL PHENOMENA AND PKOGEESS. 



the south (the sixth ridge of Schroter). On 

 that date there was not the slightest indication 

 of a shallow crater, nor the least appearance in 

 the surface round the cone which might be 

 considered indicative of its becoming a white 

 spot as the sun rose above it. The termina- 

 tor was a little east of the cone, and the next 

 ridge beyond the cone toward the east was be- 

 coming visible. Mr. Huggins, Mr. Carpenter, 

 and Mr. Penrose observed Linne the same 

 evening, with the same results obtained by Mr. 

 Birt. Mr. Carpenter also gives the crater open- 

 ing on the cone. Eev. T. W. Webb made ob- 

 servations confirming those of the other gen- 

 tlemen. The portion of the Mare Serenitatis 

 on which the cone was seen is so surrounded 

 by ridges as to be easily taken for a large shal- 

 low crater, and it may be that some of the dis- 

 cordances between observers may be thus ex- 

 plained. Mr. Birt remarks that we are greatly 

 ignorant of the true nature of the moon's sur- 

 face. The extent of our knowledge appears 

 to be of a twofold character : First, we per- 

 ceive differences of color and brightness, from 

 which we infer that the surface consists of dif- 

 ferent materials reflecting different degrees of 

 light, and also of tint. Second, the presence 

 of shadow reveals to us manifest irregularities 

 of surface as regards level, elevation, and de- 

 pression. "With the nature of the surface 

 beyond these two characteristics we are un- 

 acquainted, and can only trace out slowly 

 certain analogies with phenomena that are 

 familiar to us on the earth's crust. 



Other supposed Changes in the Moon. Herr 

 J. F. Julius Schmidt, Director of the Athens 

 Observatory, notified Mr. Birt, in June, of his 

 discovery of another supposed change on the 

 moon's surface. The region of the phenome- 

 non is situated easterly, near Alpetragius. At 

 this point Madler in his Atlas has a crater al- 

 most a mile in diameter, and says, " in the far- 

 thest east shines also, with a light of 8, the 

 small crater d." This crater d, Herr Schmidt 

 proceeds to say, now no longer exists, but, in 



its place is a round spot of light more than two 

 miles broad, extremely brilliant, which has 

 quite the character of the spotLinn6 and of the 

 few others of this kind which are found on the 

 moon. The small crater south of d, which 

 Madler gives, is still distinctly visible. Schro- 

 ter has nothing about this spot of light. Lohr- 

 mann's (unedited) plate gives a very large spot, 

 almost 2 in magnitude, and a very small hill 

 inside of it. Herr Schmidt sent to Mr. Birt 

 three sketches, the first from Madler, the sec- 

 ond from Lohrmann, and the third his own. 

 Mr. Birt took an early opportunity to examine 

 the region of the supposed change. Schmidt's 

 sketch was found to be a faithful representa- 

 tion of the spot, with perhaps the exception of 

 the white spot being better defined and in 

 more striking contrast with the surface near it. 

 Two friends, who were with Mr. Birt at the 

 time, bore testimony to the accuracy of 

 Schmidt's sketch. Mr. B., of course, failed to 

 identify the features depicted by Lohrmann 

 and Madler. 



Mr. W. E. Birt communicated a paper to the 

 meeting of the Manchester Literary and Philo- 

 sophical Society, giving an account of a new 

 variable spot on the moon's surface, which ex- 

 hibited similar phenomena to those of the 

 crater Linne. The observations were made by 

 Eev. W. O. Williams, of Pwllheli, who had 

 undertaken the examination of a zone on the 

 moon's surface, of 2 of latitude, from 4 to 6 

 south. The spot in question was situated on 

 the southwestern side of the ridge forming 

 the northeastern boundary of Hipparchus. 

 Its diameter is 5.94, and magnitude 0.37, the 

 diameter of Dionysius being regarded as unity. 

 On De la Eue's photograph, February 22, 1858, 

 it appears as a spot of about 4 of brightness. 

 It is not so bright as Linne' r which is about 5. 

 On Eutherford's photograph it appears bright- 

 er than in De la Eue's, namely, 5 Linn6 

 being 6 in the same photograph. The ob- 

 servations alluded to by Mr. Birt are as fol- 

 lows: 



'Mr. Baxendell states that on the night of 

 the 3d of January, 1868, he had an opportunity 

 of examining the spot referred to by Mr. Birt, 

 with Mr. Gladstone's equatorially mounted 



achromatic of 7t inches aperture, using pow- 



* On these occasions Mr. Williams saw a small bright 

 point to the east, which he considered to be the highest 

 point of the ridge. 



