254 



NATURE 



[July i6, 1903 



tion through a *hin lens depending on the introduction of 

 the term "divergence." Mr. Muirhead defines the diver- 

 gence of a pencil of rays with regard to a refracting surface 

 as the reciprocal of the effective distance {i.e. actual 

 distance -T- refractive index) of the surface from the apex 

 of the pencil, and the divergivity of the surface as the 

 divergence it produces on a pencil of rays originally parallel. 

 Lord Kelvin's rule that " divergence after refraction equals 

 divergence before refraction plus divergivity " then applies 

 to refractions at single surfaces, and not merely to thin 

 lenses in air. 



Several articles on the subject of aerial navigation have 

 lately reached us. Early in the year M. W. de Fdnvlelle 

 discussed the general problem in the Revue des deux 

 Mondes, with especial reference to the Bradsky disaster 

 of October, 1902, and urged the desirability of not abandon- 

 ing ordinary balloon experiments in favour of attempts 

 with motor-driven balloons. In Cosmos for May 23, Lieut. - 

 Colonel G. Espitalier gave an account of the new German 

 balloon station at Renickendorf West, the installation of 

 which includes a hangar 50 metres long, 25 metres wide, 

 and 30-5 metres high. Finally, we have before us a paper 

 by Mr. W. Rickmer Rickmers, entitled " Die Beherrschung 

 der Luft " (Vienna), in which the author condemns as 

 contrary to natural laws the attempts made to navigate 

 the air by mechanically propelled balloons. 



Prof. J. Hann presented to the Vienna Academy of 

 Sciences on April 2 a treatise on the air-currents at the 

 summit of the Santis (2504 metres) and their yearly period. 

 The investigation is based upon the anemometrical observ- 

 ations for fifteen years, and the author has calculated the 

 values of the four wind components for each month, and 

 separat-ely for three five-yearly periods. It was satisfactory 

 to find a considerable agreement of the yearly period of the 

 components in each of the three lustra. The northerly 

 cojnponent attains its greatest value in January and 

 February, and its smallest value in July and August. The 

 easterly component has nearly the same yearly period as 

 the northerly, but the maximum in winter is more pro- 

 nounced, and the minimum is from June to September. 

 The contrast between the winter and summer half-year is 

 very marked. The southerly component has a still more 

 marked yearly range, with a maximum in October and 

 November, and a minimum in June. The yearly period of 

 the westerly component is less regular, but there is a 

 decided maximum in July and August, and a similar 

 minimum in April and especially in May. Among other 

 interesting problems the author also endeavours to trace 

 the relations between this yearly variati9n of the wind 

 components and the distribution of air-pressure at sea- 

 level. These are, on the whole, well marked, so that the 

 distribution of pressure at a height of a mile and a half 

 cannot differ much from that at the sea-level. The S.-N. 

 component reaches its smallest value in May and its greatest 

 in October ; the W.-E. component has also its minimum 

 in May, but its maximum in July and August, ihe re- 

 sultant is W. 29° S., and varies but little during the year. 



Dr. J. W. KiME, in an article contributed to the Scientific 

 American of June 20, gives details of some experiments that 

 show that sunlight will penetrate in a comparatively short 

 time through a considerable thickness of flesh. He bound 

 together a small negative and a gelatino-bromide plate of 

 the ordinary kind (that is, not specially sensitised for colour) 

 and put the combination between the teeth and the cheek 

 of the subject, taking suitable precautions that no light 

 should enter at the mouth. The cheek was then exposed 

 to direct sunshine in February for forty seconds, and in 

 NO. 1759, VOL. 68] 



every case it proved that the image was developable. Re- 

 productions of the results of five experiments are shown, 

 each with a different person. One man had a thick, short 

 black beard, and this lessened the exposure effect some- 

 what. Another was a negro, with a thick, dark cheek ; 

 here the diminution in the light transmitted was still more 

 marked. No steps were taken to interfere with the circula- 

 tion of the blood, and Dr. Kime considers that his experi- 

 ments show that it is not necessary, as has been stated, to 

 compress the parts to free them from blood as far as possible 

 when light is used as a surgical agent. Dr. Kime also 

 states that his experiments show why red light is valuable 

 in the treatment of small-pox. " They prove that no 

 chemical light of any consequence reaches the patient " 

 when red curtains are fixed over the windows, &c., and so 

 irritation is prevented and subsequent disfigurement 

 lessened. But as the photographic plates used were not 

 sensitive to red light, the soundness of this deduction from 

 the experimental results may be doubted. 



It is stated that the radium rays have been successfully 

 applied in the treatment of a case of cancer by Prof. 

 Gussenbauer, of Vienna. The tumour completely dis- 

 appeared as a result of the application, radium bromide 

 being made use of as a source of the rays. The early 

 publication of these details in the public Press before there 

 has been time to test the method effectually is much to be 

 deprecated. 



Prof. Finsen, of Copenhagen, in a note upon the light 

 treatment of lupus {Acad, des Sciences, Paris, June 22), 

 points out that it is necessary to employ light of the greatest 

 intensity in order to obtain penetration of the tissues, and 

 states that his results have been much better since employ- 

 ing arc lamps, using a current of 60-80 amperes, than 

 previously with 40 ampere lamps, the former penetrating 

 in 20-25 seconds to a depth which formerly occupied 4-5 

 minutes. 



Drs. Dutton and Todd, of the Liverpool Trypanosoma 

 Expedition to Gambia, have just returned to England. 

 They state that the disease occurs frequently both in natives 

 and Europeans, and that it is distributed from the sea to 

 the Upper Gambia. Besides the human disease, there is 

 also an affection of the horse in the same region, caused 

 by a trypanosoma, and resembling somewhat the " tse-tse " 

 fly disease, but being more chronic. This is in all probability 

 a disease distinct from the " tse-tse " fly disease. A mass 

 of material has been brought home which will necessitate 

 some time to work through. 



Mr. B. Timothy sends us from Waterford an abnormal 

 corolla formed by the union of several flowers, found 

 growing on the apex of the stem of a foxglove, and 

 surrounding the stem entirely. A botanist to whom we 

 submitted the specimen remarks in reply that this abnormal 

 development of a -foxglove is " a case of peloria, that is, 

 a change or revision from an irregular to a regular con- 

 dition of the flower ; in this instance there is an additional 

 abnormality, since the pistil has proliferated, i.e. instead 

 of carpels an inner flower has been formed which bears 

 stamens, but inside the carpels again have produced vegeta- 

 tive structures, the bracts." 



A FINE sample of the Okapi {Ocapia johnstoni) has 

 recently been acquired by the Hon. Walter Rothschild for 

 his collection at Tring. The modelling has been entrusted 

 to Mr. Rowland Ward. 



In vol. Ixxiv. part iii. of the Zeitschrift ftir wissenschaft- 

 liche Zoologie, Mr. R. Weinberg publishes the first of a 

 series of articles on the brains of fossil vertebrates, dealing 

 in this case with the small Tertiary perissodactyle 



