i6o 



NA TURE 



[July 29, 1922 



the state oi the industry in India is not satisfactory, 

 and recommendations for improvement in the manu- 

 facture are given. The other reports deal with 

 Indian turpentine and rosin. These have been 

 produced on a small scale for some time past in the 

 United Provinces and the Punjab, only one species 

 of pine, Pnuts loiigifolia, being tapped commercially. 

 The turpentine of this tree is unfortunately inferior 

 to thai produced in the American and French forests. 

 It appears that a much better turpentine could be 

 obtained from Pinus excelsa, another species widely 

 spread in the Himalayas, but the yield is small. 

 Pinus khasya might also be tapped in Assam and 

 Burma. The industry is at present merely in the 

 experimental stage ; but it is predicted that, with 

 energetic business methods, the total annual yield, 

 which is now trifling, might be increased in ten years 

 to 120,000 cwts. of turpentine and 430,000 cwts. 

 of rosin. 



A case in which two cuckoos were apparently 

 reared together in the same nest by a cock blackbird 

 is recorded by Miss E. R. Saunders, Newnham 

 College, Cambridge. A blackbird's nest containing 

 four eggs on which the cock bird was sitting was 

 found and observed. The fact that a dead hen black- 

 bird was found close by afterwards may account for the 

 continued presence of the cock bird on the nest. When 

 the eggs hatched, two of the nestlings were black- 



birds, the bodies of which were found on the ground, 

 while in the nest was a young cuckoo. Another 

 young cuckoo was perched on a stake within a hand's 

 breadth of the nest. Cuckoos frequent a belt of 

 trees nearby, and it seems in this case that two eggs 

 were deposited in the one nest. 



In regard to the correspondence in Nature of 

 March 9 and June 3, under the title " A Rainbow 

 Peculiarity," on the enhanced brightness of the sky 

 within the primary bow, Mr. L. C. W. Bonacina 

 writes to point out that the fact is splendidly illus- 

 trated, and duly commented upon, by Mr. G. A. 

 Clarke in his book on " Clouds " published in 1920 

 (Plate 356). 



A new classified list of second-hand scientific 

 instruments (No. 75) has been issued by Mr. C. 

 Baker, 244 High Holborn, W.C.i. As is customary 

 in these well-known catalogues, the instruments 

 are arranged in groups and there are long sections 

 dealing with microscopes, many by first-class makers, 

 and telescopes and accessories. Among the electrical 

 apparatus we notice a Marconi receiving instrument, 

 and there is also a quantity of apparatus suitable for 

 other departments of physics as well as surveying and 

 drawing instruments. Most of the apparatus can 

 be inspected at Mr. Baker's premises. A novel 

 feature is the offer for hire, at very moderate charges, 

 of field- and opera-glasses of various types. 



Our Astronomical Column. 



Skjellerup's Comet. — The identity of this comet 

 with 1902 II. (Grigg) is now very highly probable. 

 Mr. G. Merton finds, with the aid of recent Greenwich 

 photographs, that the period of Skjellerup is close 

 to 5-13 years, the other elements being nearly the 

 same as those recently given in this column. Further, 

 the following new orbit has been deduced for 1902 II., 

 which represents the observed places within a few 

 minutes of arc, an amount well within their probable 

 error : 



T=I902, July 2-52 G.M.T. 

 " = 346° 4 1 ') 



£2 = 222° 40' ]• I902-0 



*= 9° 4' I 

 94 = 48° 12' 

 log = 0-4662 

 Period = 5-004 years. 

 The period was assumed, since the observations are 

 not nearly precise enough to determine it. The other 

 elements are fairly near those of Skjellerup. The 

 differences are explicable by the fact that there was a 

 very near approach to Jupiter at the beginning of 

 1905. By the above elements the comet was then in 

 Longitude 29J- , N. Lat. 2°, log r 0-7081 ; Jupiter was 

 in Longitude 32°, S. Lat. i°, log r 0-6959. 



The Paris Astrographic Catalogue. — M. Jules 

 Baillaud notes in Comptes rendus for July 3 that 

 tins Catalogue, which extends from North Declination 

 18° to 24°, is approaching completion, and it is ahead} 

 possible to give data about the number of stars per 

 plate in the different parts of the zone. He does this 

 in two ways : (1) the uncorrected numbers, (2) the 

 numbers after allowance has been made for variations 

 due to imperfectly clear skv, less sensitive plates, etc. 

 These have been estimated by comparing the over- 

 lapping portions oi adjacent plates. Both sets of 

 numbers are shown graphically. There are two steep 



peaks in the curve at 6 h and 2I 1 ' R.A., where the 

 zone intersects the galaxy. The curve indicates 

 1 100 stars per region of 6° x6°-6 at 6 1 ' R.A., and 1200 

 stars at 2i h R.A. 



The minima are at 3 11 and i4 h R.A., where the star 

 numbers are 150 and 70 respectively per 6° x 6°-6. 

 There is thus a 14-fold range in star-density. It 

 will be noted that the minima do not fall symmetric- 

 ally between the maxima. 



Observations of Mars at Setif, Algeria. — M. R. 

 Jarry-Desloges has sent a report to the Paris Academy 

 of Sciences of observations which he and M. G. 

 Fournier have made this year (Comptes rendus, July 

 3). They have used two refractors, apertures 37 cm. 

 and 26 cm. ; it is noted that the smaller has practi- 

 cally no secondary spectrum, although there are only 

 two lenses in the objective. While this is ad- 

 vantageous in most cases, M. Fournier finds that 

 for the purpose of detecting slight colour-differences 

 on the planets the former is preferable. 



Some of the dusky regions in the southern hemi- 

 sphere of Mars were seen to be covered with a misty 

 veil, and M. Desloges notes that this was also seen 

 in 1909 when the season on Mars was the same. He 

 also directs attention to the difficulty of tracing the 

 I southern boundaries of these dusky regions : a 

 ! similar difficulty was experienced in 1907, but in 

 intermediate years these boundaries have been well 

 defined. The' misty veil is stated to be lifting, so 

 that by June the boundaries could be traced. As a 

 change that is probably not seasonal he adduces 

 the present great development of the system Lacus 

 Moeris, Nepenthes, Thoth, to the left of Syrtis 

 Major. These features were not seen in 1907. 



I ai us Phcenicis is large at present, and Lacus Solis 

 1 girdled by a system of dark streaks. Fons Juventae 

 has also been seen. 



NO. 2752, VOL. I IO] 



