192 



NATURE 



[December 24, 1891 



A similar expression, in which r-^ is written for r^, and r^ for r,, 

 gives the value of Aj. The phase angle between the currents is 

 given by 



tan(«^ + <!») = . 



(...p|)(^.pi)-P=(^- 



('.-'i)(--p:>Ki-«)' 



-(i-K 



cosa 



. tano 



The expression for <^ shows that the phase of the current in cir- 

 cuit Aj is independent of the resistance r^. On the other hand, 

 varying r^ alters <p. It was also pointed out that tan (<^ + i|/) is 

 generally greater than tana. — Prof. J. Perry, F.R.S., read a 

 paper on struts and tie-rods laterally loaded. He pointed out 

 that, in the case of struts, a slif^ht want of straightness may con- 

 siderably reduce the breaking load. Even if a strut be originally 

 straight and the thrust properly distributed, its weight usually 

 produces lateral loading and consequent bending. Similarly, 

 centrifugal force produces lateral loading in connecting rods. 

 For some years the author has given his students practical ex- 

 amples of struts and tie-rods to work out, taking into account 

 ihe effect of lateral loads. The chief results obtained, together 

 with a general treatment of the whole subject, are embodied in 

 the paper. Where the curves of bending moment and the de- 

 flections due to lateral loading can be easily developed by 

 Fourier's series, solutions can readily be found. Simple cases 

 of uniformly loaded struts and tie-bars have been fully worked 

 out, and also the case of locomotive coupling rods. In one 

 problem on the latter subject, a rectangular cross-section was 

 chosen, and the proportions of depth to breadth determined so 

 as to make the rod equally strong in the two directions when 

 running at various given speeds. With cranks 12 inches long, 

 the results show that, at a speed of 390 revolutions per minute, 

 the ratio of depth to breadth must be infinite, so as to give equal 

 strength, so great is the influence of the lateral loading due to 

 centrifugal force, when combined with the thrust. Horizontal 

 tie- rods loaded by thrir own weight have been investigated, and 

 the tensions required to neutralize compression due to bending 

 determined. A steel bar, I inch diameter and 48 inches long, 

 was used as a strut, with a thrust of 1500 pounds. The maximum 

 stress, due to bending by its own weight alone, was 810, and on 

 applying the thrust the maximum stress was raised to 23,190, or 

 about 26 times that due to lateral loading alone. More complex 

 cases have also been treated, the results of which are given in the 

 paper. 



Paris. 

 Academy of Sciences, December 14. — M. Duchartre in the 

 chair. — On the distribution of prime numbers, by M. H. Poin- 

 care. — On the fixation of nitrogen by arable soils, by MM. Arm. 

 Gautier and R. Drouin. The conclusion is drawn that only 

 soils containing organic matter fix the free or ammoniacal nitro- 

 gen of the atmosphere, even in the absence of plants, and that 

 the organic matter existing in all arable soil is an indispensable 

 intermediary in this fixation of nitrogen. — On the camphoric and 

 isocamphoric esters, and the constitution of the camphoric acids, 

 by M. C. Fritdel. — Remarks on the history of supersaturation, 

 by M. Lecoq de Boisbaudran. The author gives some notes, 

 made by him in 1866, on the subject of supersaturation, which 

 are in agreement with the phenomena of solution observed in 

 recent years. — Observations of Borrelly's asteroid (Marseilles, 

 November 27, 1891), made at Paris with the East Tower equa- 

 torial, by Mdlle. Klumpke. Observations for position were 

 made on November 30, December 2 and 5. — On integrals of 

 the second degree in problems of mechanics, by M. R. Liou- 

 ville. — On a class of congruences of lines, by M. A. Petot. — On 

 the actual state of geodetic and topographic works in Russia, 

 by General Venukoff. — A brief note on the maps of Russia, 

 prepared under the direction of General Kowersky. — On circular 

 polarization, by M E. Carvallo. — On a thermo electric standard 

 of electromotive force, by M. Henri Bagard. The author has 

 experimented with thermo-electrolytic couples consisting of two 

 liquids, one an amalgam of zinc, containing a known proportion 

 of this metal, and the other a solution of sulphate of zinc. He 

 finds that such a couple is absolutely constant between two 

 given temperatures, its electromotive force between 0° and f 

 being given by the formula — 



Eo' = 0-001077/ + 0-00000090/2. 

 NO. I I 56, VOL. 45] 



And it is not necessary to exercise any great precision in the 

 determination of the weight of zinc dissolved in the known 

 weight of mercury to form the amalgam, for the variation of the 

 electromotive force when the couple is at the temperatures 0° 

 and 100° appears to be onlyo-oooi volt when the proportion of zinc 

 was varied from 0-00025 to 0-00075 the mass of the mercury. — The 

 three basicities of phosphoric acid, by M. Daniel Berthelot. The 

 basicities have been investigated by the author using a method 

 of determining the electric conductibilities of phosphoric acid 

 solution, and of the same with varying quantities of soda, potash, 

 or ammonia respectively added. The conclusion is drawn that 

 monobasic and bibasic phosphates are stable even in dilute 

 solution, and ihat the tribasic alkaline phosphates are nearly 

 completely dissociated in dilute solution. Phosphoric acid 

 differs completely from the true tribasic acids as the monobasic 

 and bibasic salts of the latter are partially dissociated by water, 

 and the tribasic salts, on the contrary, are stable in solution. — 

 Salts in solution, sodium sulphate and strontium chloride, by M. 

 A. Etard. — A green solid chromic sulphate, by M. A. Recoura. 

 It has the formula Cr2(S04)3,liH20. — Bismuthic acid, by 

 M. G. Andre.— On the distillation of oil, by M. Pierre 

 Mahler. — A new porcelain, asbestos porcelain, by M. F. Garros. — 

 On the presence of reticulated tissue in the muscular walls of the 

 intestines, by M. de Bruyne. — On the first phases in the A^vq- 

 \ox>mQn\. oi Crustacea edriophthalma, by M. Louis Roule. — On 

 Gymnorhynchus reptans, Rud., and its migration, by M. R. 

 Moniez. — On the rdle of the foot as a prehensile organ in Hin- 

 doos, by M. Felix Regnault. Many travellers have remarked 

 on the ability possessed by most Hindoos of using the foot as 

 well as the hand in work of all descriptions. M. Regnault has 

 made some measurements of the lengths of the feet and toes of 

 a number of natives, and draws some conclusions therefrom as 

 to the adaptation " of the organ to the function." — On the dis- 

 covery of Tertiary shells in the volcanic tufa of Limburg (Grand 

 Duchy of Baden), by M. Bleicher.— The circulation of winds on 

 the surface of the earth : fundamental principles of the new 

 theory, by M. Duponchel. 



CONTENTS. PAGE 



Botanical Nomenclature. ByW. Botting Hemsley, 



F.R.S 169 



Applied Thermodynamics. By Prof. A. G. Green- 

 hill, F.R.S 172 



British Flies i73 



Our Book Shelf:— 



"Wright: " Principles of Agriculture " I73 



Dyer and Whitcombe : " Elementary Trigonometry " 174 

 Letters to the Editor : — 



Opportunity for a Naturalist. — Dr. P. L. Sclater, 



F.R.S 174 



Warning Colours. (Il/ustrafed.)— Edward B. Poul- 



ton, F.R.S. ; W. L. Distant 174 



A Difficulty in Weismannism.— A. H. Trow . . .175 

 Destruction of Immature Sea-Fish. — Alfred O. 



Walker 176 



The Salts in Natural Waters.— F. H. Perry Coste; 



Robert B. Hay ward, F.R.S .176 



Peculiar Eyes.— E. B. Titchener 177 



Alleged Pseudopodes of Diatoms. — Alfred W. Ben- 

 nett 177 



Intelligence in Birds.— Joe 177 



A New Locality for Meteoric Iron, with a Pre- 

 liminary Notice of the Discovery of Diamonds in 

 the Iron. (Illustrated.) By Prof. A. E. Foote . . 178 

 The Severe Gale of November 11. (^With Charts.) 



By Chas. Harding 181 



Notes 182 



Our Astronomical Column :— 



Capture of Comets by Planets • 186 



Law of Limiting Apertures 186 



Connaissance des Temps 186 



Orthography of Geographical Names x86 



The Eclipse of January I. {Illustrated.) By W. . 188 

 Simple Proof of Euclid II. 9 and 10. {With Dia- 

 grams.) By Miss Hilda Hudson 189 



Scientific Serials 189 



Societies and Academies 190 



