290 



NA TURE 



[August 26, 1922 



Golding, Orr, and Prof. T. B. Wood have promised 

 to take part. The other joint discussion is also with 

 the Economics Section, and should prove of wide 

 interest, as the subject is " The Possibility of In- 

 creasing the Food Supply of the Nation." Sir John 

 Russell, Sir T. H. Middleton, Mr. C. S. Orwin, and 

 Prof. Somerville have promised to speak from the 

 agricultural side. Sir A. Daniel Hall is reading a 

 paper on " Land Reclamation on the East Coast,'' 

 and an excursion to see natural and artificial warp- 

 land should be interesting in this connexion. Prof. 

 T. B. Wood is contributing a paper embodying some 

 of the results which have been obtained in the work 

 at the Animal Nutrition Institute at Cambridge. 

 Among other interesting papers are several dealing 

 directly or indirectly with the use of lime in the 

 improvement of soil conditions, and with the evapora- 

 tion of water from soil. Horticulture and the nutri- 

 tion of fruit trees will be dealt with by Mr. H. V- 

 Taylor and Prof. B. T. P. Barker, and farm costs 

 in Yorkshire by Dr. A. G. Ruston. In addition to 

 the excursions already mentioned another has been 

 arranged to enable members to see something of the 

 farming of the Yorkshire Wolds, and it is also hoped 

 to visit some of the oil-cake factories in Hull. 



The Toronto correspondent of the Times announces 

 that the Quebec Government has decided to set aside 

 about 22,000/. for the purpose of establishing a 

 Radium Institute, under the control of the University 

 of Montreal, for the experimental treatment of cancer. 



According to the Spanish journal Iberica, two 

 underground railways are now in course of construc- 

 tion in Barcelona, viz. the Ramblas-Gracia, of a 

 total length of 3400 metres, and the Puerto branch, 

 1800 metres in length. The two lines, which will 

 be double-track systems, are of 1-435 metres gauge. 

 The construction of the system will be a matter of 

 some difficulty, as most of it will be underground 

 tunnel-driving, although a certain part, serving 

 traffic in the busiest part of the city, will be in the 

 open. Little difficulty is experienced as regards 

 water, because most of the ground through which 

 the tunnels will be driven consists of a thick stratum 

 of quaternary clay, superimposed in places by strata 

 of hard limestone marl. The method of construction 

 adopted is the Belgian system. The diameter of 

 the tunnels on the straight will be 7 metres, and in 

 curves, etc., 9-95 metres. 



A correspondent informs us that the admirable 

 drawings referred to in a review of Messrs. Heron- 

 Allen and Earland's report on Antarctic Foraminifera 

 in Nature of August 19, p. 241, were bv Miss 

 M. II. Brooks and not Mr. M. H. Brooks as therein 

 stated. 



The Cambridge University Press promises for the 

 autumn " The Air and its Ways," by Sir Napier Shaw. 

 The volume will contain the Rede Lecture for 1921, 

 and other contributions to meteorology, for schools 

 and colleges. 



Comets.— A photograph of Skjellerup's Comet, 

 19226, was obtained on July 31 at Greenwich : it con- 

 firms the short period, which appears to be very close 

 to 5 years, thus making it definitely the second shortest 

 cometary period. That of Encke's Comet is 3J years, 

 that of Tempel's Second Comet is 51 years. The 

 identity with Grigg's Comet, 1902 II, is rendered almost 

 certain, since both the period and the other elements 

 accord closely. The perihelion distance has increased 

 considerably, but only by an amount comparable 

 with that which has occurred in the case of the Comet 

 Pons-Winnecke. 



The Jouniai des Observateurs of August 15 contains 

 a series of observations of Reid's Comet, 1922a, made 

 at Santiago da Chili by Rosauro Castro. There are 

 twenty-two days of observation, from February 6 to 

 March 31. The places of the comparison stars are 

 taken from the Perth Astrographic Catalogue. The 

 comet was observed for 2 J months, so that there is 

 ample material for deducing the orbit. As the later 

 observations deviate considerably from Mr. Wood's 

 ephemeris, there is some reason to suspect appreciable 

 departure from a parabola. 



M. Kamensky has made in Astr. Nachr. 5168 a 

 very elaborate investigation of the perturbations of 

 Wolf's Periodic Comet from 1884 to 1919, due to 

 Venus, Earth, Mars, Jupiter, and Saturn. The comet 

 was observed at five apparitions (1884, 1891, 1898, 

 191 1, 1918), and the normal places are all closely 

 satisfied by the final elements, the largest residual 

 being 8"-6. The perturbations during the above 

 period have been small, the range of the mean daily 

 motion being from 5i8"- 4 in 1898 to 523"-8 in 1884, 

 or 1 per cent. There is, however, a near approach to 

 Jupiter in 1922, wliich is likely to produce notable- 



NO. 2756, VOL. I 10] 



Our Astronomical Column. 



changes in the orbit, making it quite doubtful whether 

 it will ever be seen again. M. Kamensky promises 

 to investigate them. It is to be hoped that others 

 will emulate him in similar researches on other periodic 

 comets. Those of d'Arrest, Pons-Winnecke, and 

 Tuttle are all in need of such work. 



The Problem of Three Bodies. — It has long been 

 recognised that the analytical solution of the general 

 problem of three finite masses, moving under their 

 mutual attraction, cannot be obtained in a form that 

 is of practical utility. Something can, however, be 

 learnt of the circumstances of motion, by studying 

 particular cases by the method of mechanical quadra- 

 tures. Researches of this kind are being pursued at 

 Copenhagen Observatory under the direction of Prof. 

 E. Stromgren. Some of the results were published 

 in the Jubilee Number of Astronomische Nachricliten, 

 and are now reprinted as a brochure. There are two 

 cases of special interest where the masses are as 1, 

 2, 1, the largest being in the centre. The first is an 

 approximation to an " orbit of ejection," and involves 

 periodic near approaches. The outer masses describe 

 curves resembling limacons (without loops or cusps), 

 while the central one describes a curve resembling 

 ill' inverse of an ellipse with respect to the centre. 

 The other case is an approximation to the case of 

 the arrangement of the three masses at constant dis- 

 tances along a rotating straight line. When the con- 

 ditions for the straight line are slightly departed from, 

 each body describes a small loop ; that of the central 

 body is practically an ellipse with its major axis 

 perpendicular to the rotating line. In each case the 

 motion is periodic, and the curves repeat themselves 

 indefinitely. 



