NATURE 



[June 30, 1904 



ire. M. B^nard urges the utility of having the expedition 

 composed of two vessels in touch with each other by means 

 of wireless telegraphy. The expedition should take three 

 vears, but be provisioned for five. It would not cost more 

 than 1,500,000 francs (60,000!.). The assembled company 

 signed a memorandum declaring this expedition to be of 

 scientific utility. 



.■\t a recent meeting of the Royal Photographic Society, 

 Mr. Conrad Beck described the unofocal for unifocal) photo- 

 g-raphic objective which has been worked out by Dr. Stein- 

 beil, of Munich. The principle of the new construction 

 consists in the employment of positive and negative lenses 

 all of which have the same focal length and the same mean 

 index of refraction, thus overcoming the difficulty of satisfy- 

 ing the " Petzval condition." A positive focus is obtained 

 by separating the positive and negative elements. An 

 example with a maximum aperture of //'4-5 appears at 

 first sight like a symmetrical triplet consisting of three 

 single lenses, with the central negative lens divided to allow 

 space for the diaphragm. But the inner faces of the two 

 negative lenses are concave to each other. In the series 

 with an aperture of //6, there is a greater space between 

 the negative elements, each of which is much nearer to the 

 outer positive component that it is more immediately 

 associated with. Mr. Beck stated that even the //4-5 lens 

 gives telescopic central definition, perfect freedom from dis- 

 tortion and flare, and a flat field of 60° well corrected for 

 astigmatism. An incidental advantage of the construction 

 Is that it gives a more even illumination, as oblique beams 

 iire transmitted more fully than when the elements of the 

 combinations are in contact. 



The Paris correspondent of the Times states that M. Henri 

 ■de la Vaulx is now completing his preparations for a third 

 Mediterranean cruise in a specially constructed balloon, 

 some particulars of which were given at Monday's sitting 

 ■of the Academy of Sciences. M. de la Vaulx will employ 

 a 20-horse power engine of the automobile type, attached 

 to the car, which will work an .iluminium screw seven 

 metres in tliameter. 



.\ coRRKsro\D5NT informs us that the optical illusion 

 mentioned in N.^tl-re of June 2 (p. 107) is described in the 

 Proceedings of the Royal Society of Edinburgh (vol. x., 

 1S78-C)). In the experiments described in that paper circular 

 Totating discs, and also travelling bands of paper, were used 

 for exciting the eye, and it is shown that whatever the 

 nature of the motion impressed on the eye, the surface 

 afterwards looked at appears to move in the opposite direc- 

 tion. If a rapidly flowing stream, for instance, be looked 

 at steadily for a time, and the eye afterwards directed to the 

 bank, part of the bank will seem to flow through the middle 

 ■of the field of view. The image of the part of the bank that 

 tails on the part of the retina affected by the image of the 

 moving water seems to flow slowly in a direction contrary 

 to that of the stream, causing that part of the solid earth 

 to appear as if it had become plastic. 



We have received from M. A. Lancaster the Aiinuaire 

 Meteorologique of the Royal Observatory of Belgium for 

 1904. For sixty-eight years the observatory published 

 annals devoted to astronomy and meteorology combined, but 

 «ince 1901 each science has been dealt with separately. 

 The work consists of some 660 pages, and, in addition to 

 monthly and seasonal meteorological data for various places, 

 •contains some valuable papers by M. Lancaster and others 

 connected with the service, including the motions of cirrus 

 <louds, and the dispersion of hail clouds, by M. Vander- 

 NO. 1809, VOL. 70] 



linden. The latter subject is still a controversial matter, 

 and although the results hitherto attained by shooting and 

 other methods are not generally considered satisfactory, the 

 experiments are likely to be continued for some years. 



The Transactions of the South African Philosophical 

 .Society (vol. xv., part i.) contain an important paper by 

 Mr. J. R. Sutton on South African rainfall, being the fifth 

 of a valuable series of studies on meteorological subjects 

 which have appeared in the same publication. The tables 

 exhibit the daily and monthly rainfall at Kimberley re- 

 corded by Mr. F. W. Matthews between 1877 and 1002. 

 together with the diurnal variation and other useful details : 

 also the monthly and annual rainfall at a large number of 

 selected stations. The values relating to Kimberley have 

 been discussed statistically and by the process of harmonic 

 analysis. The yearly falls from Mr. Matthews's series vary 

 from 9-34 inches in 1878 to 3i^30 inches in 1891. The 

 greatest average annual fall occurs at Maclear's Beacon, on 

 Table Mountain (8681 inches), and the least at Port Kolloth 

 (246 inches). Speaking of the Kimberley values, Mr. Sutton 

 states that March is the wettest and July the driest month, 

 the increase or decrease from one to the other being gradual. 

 Referring to South .\frican rainfall generally, outside the 

 Cape Peninsula and west coast, the author concludes that 

 rainfall decreases on the whole with distance from the coast, 

 and that it occurs with a high barometric pressure at Durban 

 and a low pressure at Kimberley ; it comes chiefly with 

 south-westerly winds at the former station and with north- 

 easterly winds at the latter. The principal barometric dis- 

 turbances come from the south. 



.\ SM.\LL brochure, in which .Mr. G. .\I. Woodrow treats 

 of the cultivation and varieties of the mango, " the choicest 

 fruit of Hindustan," has been published by Mr. Alexander 

 Gardner, of Paisley, and can be obtained from the office 

 of the Gardener's Chronicle and certain agents in India. 



In the matter of floral variation, several of the violet- 

 offer an attractive field of study, and a paper by Mr. C. K. 

 Britton dealing with floral variations among Surrey 

 violets will be found in the Journal of Botany (May). The 

 most important aberrations occur in the corolla, where, in 

 the case of I'iola hirta, all stages, from the normal single- 

 spurred petal to the symmetrical condition of five-spurred 

 petals, were observed. The condition of regular symmetry 

 in the case of Yiola Riviniana appears to be produced by 

 the suppression of the spur, but the petals are all slightly 

 pouched at the base. 



The principal historical events and appointments con- 

 nected with the Royal Botanic Gardens, Ceylon, are 

 summarised by Mr. J. C. Willis in No. 10, vol. ii., of the 

 Agricultural Journal. The expansion of the gardens has 

 not only included the formation of five branch institutions 

 situated in different climatic regions of the island, but 

 during the term of office of the present director the scien- 

 tific staff has been increased by the appointment of several 

 specialists. Although the introduction and investigation of 

 plants of economic value have been carried out in Ceylon 

 since the institution of the gardens in i860, there has been 

 a gradual change in the scope of the work, and systematic 

 collection and identification have given place to physiological 

 research and experimental cultivation. 



The skull of the dinosaur Triceratojis serrntus is described 

 by Dr. R. S. Lull (Bull. Amer. Mus. Nat. Hist., .xix.). 

 A figure of the palatal aspect shows the extreme length to be 

 about 6 feet 4 inches. 



