58 



NATURE 



[May 2 1 1908 



shot at the Crocodile River; a white egg was also 

 found in the nest of a Cape wagtail, which was 

 allowed to hatch to make identity certain ; further, we 

 took a white egg from the nest of the little red- 

 vented tit-babbler. . . . The usual host is the Cape 

 sparrow, both of us having taken the cuckoo's eggs — 

 coloured like those of the sparrow — from the nests 

 of this bird." Unfortunately, there is no information 

 as to whether there are "white-egged" and 

 " coloured-egged " strains of cuckoos in Africa, or 



Fig. 2.— Black-shouldered Kite. 



' .Sketches of South .\frican Bird-life 



whether the same bird may lay white or coloured 

 eggs according to circumstances. 



The book is a welcome addition to South African 

 ornithological literature. 



TH£ ROYAL SOCIETY'S CONVERSAZIONE. 



THE first of the two conversaziones given annually 

 by the Royal Society was held at Burlington 

 House on Wednesday of last week, May 13- The 

 guests were received by Lord Rayleigh, president of 

 the society, and included leading representatives of 

 many branches of intellectual activity. There were a 

 large number of exhibits, illustrating methods and 

 results of recent scientific work, and in the course of 

 the evening demonstrations were given in the meeting 

 room by Mr. C. V. Boys, F.R.S., on the dynamics 

 of the game of diabolo, Mr. Francis Fox, on the oper- 

 ations involved in the saving of Winchester Cathedral 

 and other ancient buildings, and Mr. C. Gordon Hewitt, 

 on the natural history of the house-fly. Following our 

 usual practice, we give a summary, with a few addi- 

 tions, of the descriptive catalogue of exhibits, and 



NO. 2012, VOL. 78] 



so far as possible have grouped together the exhibits 

 referring to related subjects. 



The British Contribution to the International Investi- 

 gation of the Upper Air, 1907-8; The investigation of the 

 upper air under the auspices of the " Commission Inter- 

 nationale d'A^rostation scientifique " is now fulh' organised. 

 This country has taken part in the work unoftlcially since 

 1902, and officially since 1904. The investigation as carried 

 on in this country is three-fold. The first part consists in 

 measurements of temperature, humidity, and wind velocity 

 at different levels up to about 10,000 feet, by 

 meteorographs raised by kites. For the second part, 

 automatic traces of the relation between pressure 

 (height) and temperature are obtained by means of 

 meteorographs borne by unmanned balloons (hallons- 

 sondes). The balloons are arranged to reach heights 

 up to 22 kilometres in about two hours, and then 

 to burst and descend. The finder is invited to re- 

 turn the instruments, and claim a reward. For the 

 third part, the "bearing and elevation of small pilot 

 balloons are observed at measured intervals of time 

 by one or two theodolites, and the motion of air 

 currents at different levels is computed from the 

 observations. The exhibits were bv Dr. \V. N. 

 Shaw, F.R.S., Mr. J. E. Petavel, F.R.S., and Mr. 

 W. A. Harwood, Mr. C. J. P. Cave, Captain C. H. 

 Ley, Mr. Eric S. Bruce, and the Director-General 

 of the Survey Department, Egypt ; they illustrated 

 the methods referred to and the results obtained by 

 British investigators. 



The Astronomer Royal: (i) Photograph on which 

 the new eighth satellite of Jupiter was discovered 

 by Mr. P. Melotte, showing also the sixth and 

 seventh satellites, and photograph of the ninth satel- 

 lite of Saturn (Phcebe) ; (2) diagrams of positions 

 of Jupiter's and Saturn's distant satellites, from 

 photographs taken at the Royal Observatory, Green- 

 wich, with the 30-inch reflector ; (3) drawings of 

 the solar corona at the eclipses of 1898, 1900, 1901, 

 and 1905, made by Mr. W. H. Wesley from the 

 original negatives; (4) eclipse of 1901, May 18, from 

 photographs taken in Mauritius, and eclipse of 

 11105, .August 30, from photographs taken at Sfax, 

 Tunisia. — Solar Physics Observatory, South 

 Kensington : (i) Enlarged photographs of stellar 

 spectra ; (2) spectrum of a sun-spot ; (3) spectro- 

 heliograph disc photographs, taken in "K" light; 

 (4) photographs of prominences, taken in " K " 

 light; (5) photograph of .'\berdeenshire stone circle 

 with Cornish circle for comparison. — Mr. J. 

 Franklin-Adams : (i) Machine for counting stars 

 upon the 15 inch by 15 inch plates of the Franklin- 

 .\dams chart. .As the number of stars upon this 

 chart is estimated at 23,000,000, only special areas — 

 selected by Prof. Kapteyn, of Groningen — will in the first 

 instance be counted, this machine, by Troughton and 

 Simms, is designed to work with such accuracy that 

 regions adjacent to the selected areas may afterwards be 

 added without omissions or overlappings. (2) Machine for 

 drawing precession lines upon the plates of the Franklin- 

 Adams chart. This machine has been designed to draw to 

 a hundredth of a millimetre, if necessary, precession lines 

 giving star places at epochs 1855, 1875, 1900, and 1925, 

 both in Right .Ascension and Declination. 



Mr. ]. S. Wilson and Mr. W. Ctore : India-rubber models 

 and apparatus used for the investigation of the distribu- 

 tion of stress in dams (Fig. i). The model, which rests 

 on the top of the trestle, consists of a slab of india-rubber 

 cut to represent the section of a masonry dam, together 

 with its foundation and substratum. The water pressure 

 against the dam is reproduced by plates pulled against 

 the upstream face of the model by cords passing over 

 pulleys and attached to weights. The correct ratio between 

 the density of the fluid represented by that pressure and the 

 density of the masonry (i : 2-25) is maintained by suspend- 

 ing a large number of weights from pins passing through 

 the model at vmiformly distributed points. To obtain 

 strains large enough to measure, both densities are 

 magnified forty times. Photographs are taken of the model 

 and the svstem of lines ruled on it, one when unstrained 



