April 29, 1920] 



NATURE 



275 



Katanga line, would complete a Cape-to-Cairo route 

 within British territory. 



The annual report on the Nile gauges and rainfall 

 of the Nile Valley ceased publication during the war, 

 the last number being that for 19 12, published in 

 19 14. The work has now been transferred from the 

 Survey Department to the Ministry of Public Works, 

 which publishes the records of the gauges for 19 13 to 

 19 18 as Physical Department Paper No. i. In order 

 to reduce the number of data, five-day means are 

 given for twenty representative gauges between the 

 delta barrage and Entebbe, on Lake Victoria. Tables 

 are also given of monthly means for each of the six 

 years, and the actual discharges on certain days at 

 several stations on the main Nile and Blue Nile. 

 These discharges were measured by the current meter, 

 which Mr. H. E. Hurst, the author of the report, 

 calculates has a probable error of not more than about 

 3 per cent. 



Two papers published recently by , the Ministry of 

 Agriculture and Fisheries (Series II., Sea Fisheries, 

 vol. iv., Nos. I and 2) deal with the method of deter- 

 mining the age of fishes by inspection of the scales. 

 It is well known that the material of the latter 

 structures is laid down in more or less regular layers, 

 and that there are differences between the substance 

 deposited in the warmer, and that laid down in the 

 colder, months. By counting these rings, then, an 

 estimate of the age of the fish can be made. The 

 method is not applicable to all scale-bearing fishes, 

 and there has been much discussion as to its trust- 

 worthiness. In the first of the papers to which refer- 

 ence is here made Mr. R. E. Savage describes the 

 structure of various scales as elucidated by special 

 reagents and studied under polarised light. In the 

 second paper Miss R. M. Lee has made a critical 

 review of most of the important memoirs dealing 

 with scale-markings, and subjected selected series 

 of measurements to mathematical tests. Her general 

 conclusions are that, with certain precautions, the 

 method is trustworthy. 



The climate and weather of the Falkland Islands 

 and South Georgia is the subject of a memoir com- 

 nilf'd by Mr. C. E. P. Brooks, and published by the 

 ' orological Office as Geophysical Memoir No. 15. 

 Falkland Islands observations are all from Cape 

 IVmbroke lighthouse with the exception of a few 

 di>;continuous series from Port Stanley. The Cape 

 iibroke records date from the visit of the Scptia in 

 1, when Dr. W. S. Bruce and Mr. R. C. Mossman 

 led observations there in connection with their 

 rds in the Weddell Sea. The scanty South 

 *rgia records are the result partly of various 

 scientific expeditions, but are mainly due to the enter- 

 prise of the Argentine Fishery Co. in Cumberland Bay. 

 Summaries of all available data, including those 

 previously published, are given in the memoir. 



The Danish Meteorological Institute has published 

 its issue for 1919 on the state of the ice in Arctic 

 seas. As usual, the publication is in both Danish 

 and English, and is well illustrated with charts. 

 Information was scarce from the Beaufort and Bering 

 Seas, Baffin Bay, and the western part of Davis 

 NO. 2635, VOL. 105] 



Strait. In Spitsbergen seas the state of ice was about 

 normal; the pack-ice off the west coast in April and 

 May disappeared in June, and did not return through- 

 out the summer. The ice in the fjords did not break 

 up until May, which is later than usual and two 

 months later than this year. The coasts of Iceland 

 were singularly free from ice throughout the year 

 except for a few days on the north-east in spring, and 

 again in summer. Icebergs on the Newfoundland 

 banks were normal in number and distribution. The 

 Kara Sea, as usual, was navigable in the south and 

 east in September, but there is no information for 

 earlier summer months. 



The attention of systematic students of the 

 Arachnida may advantageously be directed to 

 J. Hewitt's " Survey of the Solifugae of South 

 Africa" (Ann. Transvaal Mus., vol. vii., part i, 

 1919), in which clear generic and specific diagnoses 

 are illustrated by structural drawings and by a series 

 of excellently reproduced photographs. E. A. 

 McGregor's paper on the "red spiders" (Tetranychi) 

 of America (Proc. U.S. Nat. Mus., vol. Ivi., 1919) is 

 another recent arachnological publication of import- 

 ance. 



A CONTRIBUTION of importance to Cetacean embryo- 

 logy has been made by Dr. F. E. Beddard, who 

 describes (Ann. Durban Mus., vol. ii., part 4, 1919) 

 two embryos of the sperm whale of an earlier stage 

 than has hitherto been observed. The smaller, 

 measuring only 114 mm. in length, has the relatively 

 short head flexed ventralwards, so that its long axis 

 is almost at right angles to that of the body, while 

 the lower jaw projects beyond the upper; the tail-fin 

 is narrow and ovate in form. 



In a memoir on "The Theoretical Determination 

 of the Longitudinal Seiches of Lake Geneva " (Exlin. 

 Roy. Soc. Trans., vol. Hi., 1920, pp. 629-42), Messrs. 

 Doodson, Carey, and Baldwin have applied Proud- 

 man's general solution (Lond. Math. Soc. Proc, 

 vol. xiv., p. 240) to the particular case of Lake 

 Geneva. The dimensions of the lake along thirty- 

 one sections being obtained from Hbrnlimann and 

 Delebecque's map, the durations of the first three 

 periods were found to be 74-45, 35-1, and 28 minutes. 

 According to Forel's observations (with a slightly 

 different zero-plane), the period of the uninodal 

 oscillation is 735 minutes, and of the binodal oscilla- 

 tions 35-5 minutes. The positions of the nodes of 

 the uninodal and binodal oscillations are also deter- 

 mined theoretically, and agree approximately with 

 those found experimentally, although, as the authors 

 remark, the exact determination of nodes by observa- 

 tion is very difficult. Would it not be possible to 

 test the latter by observing the reflections of the 

 setting sun from the east end of the lake? Three 

 definite reflections were once seen from such a posi- 

 tion by the writer of this note. 



The Journal of the Queckett Microscopical Club 

 (vol. xiv., November, 1919) contains an interesting 

 contribution by Dr. Hamilton Hartridge on micro- 

 scopic illumination, in which the question of the 

 supposed advantages of so-called critical illumination 

 (which consists in accurately focussing an image of 



