400 . Scientific Intelligence. 



only by a few of the asteroids. The period is 546*5 days and its 

 diameter is estimated at 200 miles. It is thus the largest body 

 discovered in the solar system, exclusive of the comets, since the 

 inner satellites of Uranus were found by Lassell in 1851 ; it is 

 also b} T far the faintest object, its brightness being estimated as 

 two magnitudes less than that of Hyperion, which is assumed to 

 be of the 14th magnitude. 



Vol. liii, No. IV, pp. 75-84 with four plates. A Study of 

 Eratosthenes ; by William H. Pickering. Some paragraphs from 

 this paper are quoted below. 



Vol. lvi, No. I, pp. 1-26 with two plates. Distribution of 

 Stellar Spectra. 



Circulars: No. 83, Common's 60-inch Telescope; No. 84, 

 Carnegie Grant of 1903 ; No. 85, The anonymous gift of 1902. 



2. A Study of a Lunar Crater. — The following paragraphs, 

 which form the concluding part of the " Study of Eratosthenes " 

 by W. H. Pickering, referred to above, will be read with interest 

 in connection with the recent discussion of the features of the 

 moon (see p. 314 of the October number). The author closes the 

 detailed description of the crater and the changes in it observed 

 by him as follows : 



" Summarizing our knowledge so far, we find that there seem 

 to be four canal systems, two large and two small. They are best 

 seen in figure 11. In each there is a prominent lake from which 

 three or more canals diverge in various directions. The largest 

 of these lakes, which we will call I, is situated to the east of the 

 central peaks. Three canals radiate from it. The second largest, 

 which we will call II, is situated on the northwestern slopes of 

 the central peaks. It also has three canals. Ill, at the extrem- 

 ity of ridge A, has four or five canals radiating from it, and a 

 nearly concentric ring, similar to Solis Lacus on Mars. IV is a 

 small and very faint lake at the extreme northern end of the 

 floor, from which at least five minute canals radiate. It also is 

 furnished with a somewhat ill-defined dark ring, composed in 

 part of the lakes and canals of systems I and II. I reminds us 

 somewhat of the Syrtis Major on Mars and the two large canals 

 or branches which lead into it from the south, and form a rather 

 characteristic Y at certain seasons. 



These canal systems seem to be almost entirely independent of 

 the surface configurations. Sometimes the central lake is on a 

 mountain crest like III, and sometimes in the bottom of a valley 

 like I. The canals sometimes, as in system II, descend one slope, 

 cross a valley, and ascend another. They generally appear all at 

 once throughout their whole length, but in at least two instances 

 we have recognized a progressive motion. In one of these cases, 

 A, the direction of motion was tangential to the lake III ; in the 

 other, D, it was radial and towards the lake I. In both cases the 

 motion was down hill. D vanished on the ridge before it did on 

 the lower slopes. 



A few words may now be said on the chief objection that has 

 been raised to the theory that these changes are due to vegeta- 



