Lunar Mountains Tycho, Pictet, and Saussure, 285 



wards the nortli-wcst ; at some points it is interrupted, but, so far as can 

 be judged, it is without craters. At full moon, five peaks can be discovered 

 in the zone of Pictet, like brilliant points, which are scarcely detached from 

 the great luminous band which runs in that directioq. 



Although it is difficult to take measurements in those situations where 

 the limit of the light is^quite undetermined, yet we have made some at- 

 tempts of this kind, which we supply. 



Tycho A, western margin, has a height above the bottom of the cavity 

 of . . . . . 835 T. . 



Tycho D, western margin, . . .817 



Street^ south-western margin, . . . 698 



Pictet a, western margin, . . , 889 



From these measurements, it appears that the most marked differences in 

 elevation in the immediate neighbourhood of Tycho reach to about one* 

 third of those which exist between its principal zone and the bottom of it!5 

 own cavity.* 



Smismre is a great annular mountain, which had not previously been 

 named, and which is situated somewhat to the west of Pictet : its form upon 

 the whole is regular ; it is six German miles in diameter, and is visible at 

 full moon, because it is somewhat darker than the surrounding region. 

 The luminous bands which extend from Tycho to its eastern border are 

 there inteiTupted, and then continue in the same direction as far as its 

 western margin, which is the only example of this kind of appearance found 

 in an annular mountain of such extent. Its interior, whose brightness 

 is at 3", is flat, and exhibits only one feeble crater, placed excentrically. 

 Its zone is highest at the points j8 and a : a terrace may be seen here, which 

 appears to cease towards the western margin. The most luminous of the 

 craters wliicli interrupt the zone is marked by the letter B, and is situated 

 in 42° 25' south latitude, and 3° 36' west longitude ; four small summits 

 crown the steep zone. The luminofre bands which are situated near the 

 edges of Saussure have the same degree of brightness, with somewhat 

 clearer places towards me south. On the exterior flank, towards jS, a small 

 furrow or cleft (Rille) commences, running towards the north, which was 

 discovered on the 18th of March 1834. Two other somewhat analogous 

 valleys, which run south near 7, had previously been remarked on the 29tli 

 of March 1833. On the Avest from the point <•, proceeding towards the 

 north, there exists a great mountainous ramification, parallel to the western 

 iiiargin, and more elevated, which connects itself with the mountains of 

 Orontius. The annular mountain we have designated Saussure A, situated 

 to the west, in 43° 20' latitude, and 1° 14' longitude, is very regular, and in 

 a somewhat flat district. Beyond it, more to the south, is found the double 



* It will here be remembered, that for most of the smaller heights, and for a 

 considerable number of the mountains of the moon, Messrs Baer and Madler 

 have not taken actual measurements, or actually calculated the elevations; but 

 have limited themselves to a simple estimate of these heights, the result of a 

 visual appreciation of the length of the shadows, compared with those of the 

 neighbouring mountains, whose heights had been accurately ascertained with 

 all becoming care. / 



VOL. XXV. XO. L. — OCTOBER 1838. U 



