( 283 ) 



On the Lunar Mountains Tycho, Pictet, Snussnre ; and on the 

 Geology of the Moon. By William Beer and J. H. 

 Madler of Berlin.* 



1. Topography of the Surface of the Moon. — The lunar to- 

 pography of Messrs Beer and Madler occupies 213 quarto 

 pages, and is divided into four sections, corresponding to the 

 four sheets of their map, or to the four quadrants of the circu- 

 lar surface of the moon which is visible from the earth. The 

 authors give successively, in each section, detailed descriptions 

 of the seas, and of the different regions which correspond to 

 them, also of the mountains, cavities, and all the other ap- 

 pearances which they present. Hence, it will readily be under- 

 stood, that it is quite impossible to present any thing like an 

 analysis, properly so called. We shall, therefore, confine our- 

 selves, in presenting an idea of the method pursued by our 

 authors, to the selection of one of their descriptions, viz. to that 

 of the large spot Tycho, and of its environs, which will be 

 found at the commencement of their third section, which re- 

 lates to the south-east quadrant of the moon. And even in 

 this, we must omit certain less important details, and some 

 which have already l^een alluded to. 



Tyckoy so named by Riccioli, and which HeveKus had designed lions 

 Sinai and DeseHum Zi7t, is an annular mountain, which is \asible to the 

 naked eye during full moon ; whilst,, at the epoch of its changes, it cannot 

 certainly be distinguished except by means of a good glass, and with a 

 thorough knowledge of its precise position. It is situated, according to our 

 nine measurements, in 42° 52' 19" of the moon's southern latitude, and in 

 11° 62' 25" eastern longitude ; it is 11| German f miles in diameter (about 

 20 leagues of 25 to a degree) ; it is of a round form, and is completely 

 surrounded by a naiTow rampart of a uniform height, very like a white 

 Willi. Our measurements give to its eastern edge an elevation of 2676 

 toises above the interior surface, and a height of 1961 toises above the 



• We again avail ourselves of the able abstract of the labours of Beer and 

 Madler, prepared by M. Gautier of Geneva, for the Bibliotheque UniverseUe — 

 Edit. 



+ We must again remind our readers, that the miles in this article are German 

 miles, each being equal to about 4.6 English. The measurements of heights 

 are given in tcises, a toise being equal to 6.39 English feet, or, for general pur- 

 poses, a fathom. 



