April 2%, 1881] 



NA TURE 



619 



In order to exhibit the constancy of the lag in the occurrence 

 of the gradient variations behind those of the sun spots, as well 

 as the remarkable similarity in form of the two oscillations, I 

 have reproduced the above figures graphically in the accom- 

 panying diagram, in which the baric gradient ahnormals are 

 plotted out simultaneously with the invei-lci sun-spot ab- 

 normals : — 



It will be observed that there is an almost uniform lag in the 

 baric gradient curve behind the inverted sun-spot curve of a 

 little more tnan a year, while a variation of 'OI inches on the 

 barometer scale corresponds very nearly throughout (allowance 

 being made for the lag) to 10 on the sun-spot scale. 



As tlie strength of the prevailing west and si'Uth-west winds 

 of these regions must necessarily depend on the amount of the 

 baric gradient between places on the edge of the European 

 continent like London, and those inland, and to the north as St. 

 Petersburg, there is fair ground for concluding that the west 

 and south-west winds must on the whole be stronger in years of 

 minimum sun-spot than in those of maximum sun-spot. 



Some direct evidence in favour of this notion has already 

 been communicated to Nature by Mr. S. A. Hill and Mr. 

 Ellis of the Greenwich Observatory. 



Moreover the amount of variation in the strength of the wind 

 between London and St. Petersburg, following upon the change 

 in the barometric gradient between the two during the cycle, 

 should be enough to cause a sensible variation in the character of 

 the weather ; for according to Mr. Blanford the mean baro- 

 metric gradient over the Bay of Bengal during the south-west 

 monsoon is about o'o25 inches in 100 miles. 



Now as the distance from London to St. Petersburg is about 

 1300 miles ; in order to maintain a current of air between them 

 throughout the year equal to that of the summer monsoon in the 

 Bay of Bengal, there would have to be a total annual barometric 

 gradient of 0*0325 inches. As the range of the abnormal gradient 

 in the present case amounts to o"o8 inches it should cause a 

 variation in the wind equal to one-fourth that of the monsoon. 



For the period 1822-71 the normal mean annual gradient from 

 London to St. Petersburg is -I- o'ogS inches. The variation of 

 the abnormal is therefore nearly equal to the normal gradient. 



Taking the results just obtained with those given by Mr. H. 

 F. Blanford in his article in Nature, vol. xxi. p. 477, it may 

 be concluded that there is a barometric "see-saw" between 

 Russia and Western Siberia and the Atlantic coasts of Europe, 

 similar to that between the former districts and Indo-Malaysia. 



Just as in the latter ca-e the relation will probably be found to 

 be more marked in the winter months, and may also be found to 

 explain some of the numerous facts already ascertained regarding 

 variations in the rainfall, cloud, and temperature of Western 

 Europe, at different epochs of the sun-spot cycle. 



E. Douglas Archibald 



CONGRESS OF THE FRENCH LEARNED 

 SOCIETIES 



'X'HE session of the Congress of the French Learned Societies 

 ■'- has [lasted only three days, but has exhibited an unusual 

 amount of interest. Many papers were read in the section of 

 Science presided over by M. Milne- Edwards, the veteran member 

 of the Institute. •' 



M. Alluard summarised the results of rotation of the wind as 

 registered by anemometers at an altitude where it is not to be 

 feared that surface-friction should interfere. The number of 

 rotations from north to south was 113. Of these 83 were 

 in the positive direction, or by east, and only 30 by west ; 49 of 

 the 83 positive w ere continued to the west, and 34 stopped at 

 the south or vicinity ; consequently when a wind has come from 

 north to s luth by east, the greater probability is that it will con- 

 tinue rotating to the west. When it has rotated to the west the 

 probability is even greater that it %vill continue to the north. 

 Again, of the 49 three-quarter rotations observed not less 

 than 32 were completed, and only 17 stopped at the west and 

 vicinity. The same thing cannot be said of the negative rota- 

 tions : only 13 were from north to east, and of these only 6 were 

 from north to north by west. These results 'are a confirmation 

 of Dove's well known law. 



General Nans nity, the director of the Pic-duMidi Observa- 

 tory, announced that the new buildings on the top of the moun- 

 tain will soon be ready, and that next winter he will use them 

 for taking readings. It is curious that the last winter has been 

 one of unusual mildness in this exalted altitude. 



M. Hebert read a long paper on the formation of cyclones, 

 which he exjtlains by the influence of mountain ranges on the 

 great atmospheric currents loaded with humidity. 



M. Vidal presented a photometer b.ased on the action of light 

 on a selenium element of the ordinary construction. M. Vinot, 

 editor of Lc Ciet, presented a refractor mounted equatorially, 

 of which the price is less than 10/., with a magnifying 

 power of 150. M. Joubert gave details on the working of the 

 Trocadero Popular Observatory, which is now in constant opera- 

 tion, and where lectures on astronomical subjects are delivered 

 regularly. 



M. Guillemare read a paper on the use of soleine for lighting 

 purposes. This product has been obtained by the distillation of 

 a number of resinous matters, which have a ]?oint of ebullition 

 from 150 to 160 Centiijrade and a mean density of o'86o. When 

 they have been freed from every other matter they can be 

 used in a specially-prepared burner. This soleine can be pre- 

 pared in immense quantities in all countries where pines are 

 abundant. 



A number of interesting communications were made on 

 palaeontology and zoology, generally advocating Darwinian 

 views. 



The final sitting was presided over, as usual, by the Minister 

 of Public Instruction, and took place in the large hall of the 

 Sorbonne. A number of crosses of honour and medals were 

 distributed. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE 



O.XFOiin. — The lectures of the .summer term commence this 

 week. At the University Museum Prof. Clifton will conduct a 

 class in practical physics and will lecture informally on the use 

 of optical instruments. Mr. Stocker will give an experimental 

 lecture in mechanics, and Mr. V. Jones will lecture on mechani- 

 cal problems, in continuation of their courses last term. Prof. 

 Odling will continue his course of lectures on organic chemistry, 

 and Mr. Fisher will finish his inorganic course. 



At Christ Church Mr. Harcourt lectnres on the metals, and 

 Mr. Baynes on the theory of gases. At Balliol Mr. Dixon gives 

 an experimental lecture in elementary physics. 



In a Congregation holden on Tue-day, April 27, it was 

 resolved that candidates, not being members of the University, 

 may present themselves at any of the ordinary examinations for 

 Responsions. Last term a statute was parsed instituting an ex- 

 amination to take place in the Long Vacation. This examina- 

 tion, which can be passed by candidates before matriculation 

 into the University, is to be passed in lieu of Responsions. The 

 effect of the statute will be that all young men rnay pass Re- 

 sponsions before they matriculate, and less of their University 

 time will be consumed in getting up school work. 



The proposal to designate the unattached students as stu- 

 dents of the University Hall was lost by a large majority, go 

 voting against the propo.sal and only 9 for it. 



SOCIETIES AND ACADEMIES 

 London 

 Chemical Society, April 21. — Pr. Debus in the chair. — It 

 was announced that a ballot for the election of Fellows would 

 take place at the next meeting. May 5. — The following papers 

 were read : — On the distillation of mixtures of carbon disulphide 

 and carlion tetrachloride, by F. D. Brown. The objects of the 

 research were to find the boiling-point of every possible mixture 

 of the two liquids, and the composition of the vapour evolved by 

 any mixture when boiling. Tables and curves giving these 

 results accompany the paper. The author al-o finds that the 

 composition of the v.apour evolved is independent of the pressure 

 under which ebullition takes place — On the estimation of 

 hydric peroxide by means of potassic permanganate, by W. E. 

 Adeney.— On the oxidation of sulphurous acid, by H. P. Dixon. 

 The author finds that when sulphur dioxide, steam, and oxygen 

 are exposed to a temperature of 100° C. no diminution of 

 volume takes place, and therefore no sulphhuric acid is formed. 

 If the temperature be allowed to fall so that water condenses, a 

 slight contraction in volume is observed. — On the reduction of 

 cinnamic alcohol, by F. Hatton and W. R. Hodgkinson. 

 When this substance is heated to 100° C. for three or four days 



