May 8, 1884] 



NA TURE 



47 



season, and favour the production of dry north-west winds on the 

 plains of Western India. 



(6.) That this dependence of dry winds on the Himalayan 

 snowfall affords a criterion for forecasting the probabilities of 

 drought in North- Western and Western India. 



In setting forth the above conclusions, it is, however, neces- 

 sary not to ignore the fact that there are other conditions besides 

 those here considered which exercise a very great influence on 

 the prevalence of dry winds and drought. During the last 

 famine period in India (the years 1S76 and 1877 ; in the former 

 year in Southern India, in the latter in the North- Western 

 Provinces and Rajputana), the pressure of the atmosphere was 

 persistently and abnormally high, and this was due, as I showed 

 in the reports on the meteorology of those years, to the condi- 

 tion, probably the high density, of the higher atmospheric strata. 

 Moreover, this excessive pressure was shown to affect so exten- 

 sive a region that it would be unreasonable to attribute it to 

 the condition of any tract so limited as a portion of the 

 Himalayan chain ; and if dependent on the thermal conditions 

 of the surface, which may indeed have been the case, this land 

 must rather have been the major portion of the Asiatic con- 

 tinent than merely a relatively small portion of its mountain 

 axis. This question must remain for future inquiry. It is 

 referred to here to guard against too wide an application being 

 assigned to the action of the Himalayan snows. 



Physical Society, April 26. — Dr. Guthrie, president, in the 

 chair. — New Members: Mr. Chattock, Mr. Inwards. — Profs. 

 Perry and Ayrton read a paper on the indicator diagram of a 

 gas-engine, which was intended to teach practical engineers a 

 new method of studying gas-engine diagrams. The most recent 

 results obtained by the use of Dowson gas were stated, and it 

 was suggested that before long gas-engines will be employed for 

 the propulsion of ships. A large wooden model of an Otto gas- 

 engine enabled the operations going on during a cycle of the 

 engine to be understood. Tables were given of the constituents 

 of coal-gas and Dowson gas, the air required for combustion, the 

 heat of combustion, and the specific heats, to enable the charac- 

 teristic equation of the fluid used in the gas-engine to be deter- 

 mined. An easy method of obtaining one empirical formula to 

 represent all the diagrams which can be obtained from an engine 

 with different quantities of gas was described and its results 

 compared with observation. The effects of vibration of the 

 indicator spring in the various parts of the diagram were dis- 

 cussed, as well as the effect of the last explosion, which are pro- 

 vided for in the empirical formula. Three practical methods of 

 determining the rate, q, of gain of heat by the fluid during the 

 forward stroke were given, and a diagram was shown in which 

 this rate could everywhere be compared with the rate of doing 

 work. If W is the indicated work in one cycle, it was shown 

 that 5*64 W is the total energy of combustion of one charge, and 

 this is expended as follows : — 1 "45 W is the work done in the 

 forward stroke, 2'22 W is given to the cylinder by radiation in 

 the forward stroke, I '5 W is carried off through the exhaust- 

 pipe, o - 47 W is given to the cylinder as heat after exhaust-valve 

 opens. The rate at which the loss, 2 '22 W., by radiation 

 occurs at every point of the forward stroke was shown on a dia- 

 gram obtained from a knowledge of the temperature at every 

 point in the stroke, and when the ordinates of this diagram 

 were added to the q diagram previously described, a diagram 

 was obtained showing at every point of the stroke the rate at 

 which combustion was going on. This diagram was specially 

 important as showing the effect of dissociation in the gas-engine. 

 — Dr. W. H. Stone exhibited a simple form of siphon mercurial 

 barometer with metrical scale. Two millimetre scales are ad- 

 justed to slide easily side by side ; the lower edge of one is 

 brought on a level with the mercury in the shorter limb, and the 

 other slid up and down until its lower edge coincides with the 

 upper mercury surface. The adjustment is easily effected by an 

 observer without stooping by the use of two right-angled glass 

 prisms fitting on the upper and lower ends of a vertical glass 

 tube. — The next meeting of the Society, on May 10, will be held 

 in the Mason College, Birmingham. 



Anthropological Institute, April 22. — Prof. Flower, 

 F.R.S., president, in the chair. — The President, in welcoming 

 the Members to their new quarters, gave an outline of the his- 

 tory of the Society and of the eminent men who have presided 

 over it during the forty years of its existence. The Ethnological 

 Society, founded in 1843, and the Anthropological Society twenty 

 years later, were united in 1S71 under the title, " The Anthropo- 

 logical Institute of Great Britain and Ireland." — The Marquis of 



Lome sent to express his regret at his inability to attend ; he 

 exhibited a large collection of North American objects, including 

 a scalp taken last summer. — Sir Richard Owen communicated a 

 paper on a portrait of an aboriginal Tasmanian. The paper was 

 further illustrated by two busts and several portraits belonging to 

 the Institute. — Prof. Keane then read a paper on the ethnology 

 of the Egyptian Soudan, which was described as a region of 

 extreme complexity, a converging point of all the great races of 

 the African Continent, except the Hottentot and Bushman. 

 Although official documents such as Col. Stewart's "Report on 

 the Soudan " for 1883, recognised only "two main divisions, 

 Arab and Negro," it was shown that here was represented the 

 Hamites, Semites, Nubians, Negroes, and Bantus. Of the 

 Hamites, the chief branches were the Tibbu in Darfur, and 

 the Ethiopians stretching east of the Nile without interruption 

 from Egypt to the Equator, and including the Galla and Somali 

 south of Abyssinia, various tribes between Abyssinia and the 

 coast, and the Bejas, who occupied the greater part of the 

 Nubian Desert between Abyssinia and Egypt. The Bejas, 

 whose very existence was ignored by our officials, and who were 

 universally confounded by newspaper correspondents with the 

 Arabs, were the true aboriginal element in the country between 

 Berber and Suakim, where they recently came into collision with 

 the British forces. 



Royal Microscopical Society, April 9. — The Rev. W. H. 

 Dallinger, F.R.S., president, in the chair. — On the motion of 

 the President a vote of condolence with the R. Accademia dei 

 Lincei on the death of their president, Quintino Sella (an ex- 

 officio Fellow of the Society) was passed. — Dr. Carpenter, C.B., 

 explained in detail his reasons for considering that binocular 

 vision in the microscope took place on the same principles as in 

 the case of ordinary vision, and combated Prof. Abbe's view to 

 the contrary. A number of photographs, diagrams, and models 

 were exhibited in illustration. Mr. Crisp gave his reasons for 

 considering that Prof. Abbe was right. In ordinary vision we 

 had a perspective shortening of parts of the object, but under 

 the microscope this did not occur. In ordinary vision a lined 

 object would show the lines closer together when viewed 

 obliquely, whilst under the microscope the lines appeared the 

 same distance apart whether they were viewed by the central or 

 oblique pencils. — Mr. Bolton exhibited the interesting Rhizopod, 

 Clat lit nlina elegans, from Epping Forest, which had been found 

 to exhibit a fourth mode of reproduction by the formation of 

 flagellate mo'nads. —Mr. Guimaraens described a true Xanthi- 

 dium from Halifax coal strata. — Mr. Badcock read a note on 

 certain filaments which he had observed protruding from Surirella 

 bifrons. — Mr. Nelson explained the method which he had found 

 most suitable for examining certain bacteria. — The President 

 announced that the next meeting would be made special, to 

 consider the question of the admission of ladies as members of 

 the Society. 



Paris 



Academy of Sciences, April 28. — M. Rolland in the chair. 

 — Observations extracted from M. Verbeek's report on the 

 Krakatoa eruption of August 26, 27, and 28, 1883, by M. 

 Daubree. — Note on the problem to determine the degree of all 

 algebraic surfaces which maybe oscillatory with another surface, 

 by M. de Jonquieres. — On an extension of the law of Harriot 

 relating to algebraic equations, by Prof. Sylvester. — Memoir on 

 the conservation of stellar energies, and on the variation of 

 terrestrial temperatures, with a table showing the probable suc- 

 cession of the approximate dates of maximum and minimum 

 intensity of solar radiation, by M. Duponchel. — On the absolute 

 standard of light, by M. J. Violle. In this paper the author 

 develops the idea already formulated by him at the International 

 Congress of Electricians in 1SS1, the essential object of 

 which was to verify the principle of the method, which con- 

 sists in taking as a standard of light a metal at its point 

 of fusion. He now finds that platinum best fulfils the con- 

 ditions required of an absolute standard of light. It rests 

 on a perfectly defined and constant physical phenomenon, and 

 ci institutes a practical term of comparison with ordinary standards. 

 — Results of a series of experiments undertaken to determine 

 the dimensions of the column of mercury at zero which repre- 

 sents the unity of practical resistance, or the value of the ohm, 

 by MM. E. Mascart, F. de Nerville, and R. Benoit. — Note on 

 the application of the laws of induction to the helio-electric 

 theory of the perturbations of terrestrial magnetism, by M. Quet 

 From his own observations, as well as those of Carrington, Arm 

 strong, and others, the author infers a definite relation between 



