March 23, 1893] 



NATURE 



501 



I 



ance with the Lagrangian rule. The author then applies the 

 proposition to the case of a perforated solid with liquid irrota- 

 tionally circulating through the apertures, and shows how 

 it may be extended to any num'ier of perforated solids. 

 Incidentally it is mentioned that in equations (lo)^ and (to)^' 

 (Thomson and Tait, part i. § 327) the sign of dvj^'if should be 

 reversed. A difficulty which arises in applying the result of 

 § 319, example G, in the same work, to the motion of solids 

 through liquids is also referred to. A criticism by Mr. A. B. 

 Hasset on Mr. Bryan's recent paper and also on Dr. Burton's 

 paper was read by Mr. Elder. Mr. Basset regarrls the process 

 employed by Mr. Bryan in obtaining the equations of motion as 

 a distinctly retrograde step, and thinks the most scientific way of 

 dealing with dynamical problems is to avoid the unnecessary 

 introduction of any unknown reactions. The advantages of the 

 theory of the impulse are described by Mr. Basset, and the 

 parts which require care when applying the theory to cyclic 

 irrotational motion pointed out. Comparisons are then made as 

 regards simplicity, between the different methods of treating the 

 subject which have been used by Mr. Bryan, Prof. Lamb, and 

 himself. With reference to Dr. Burton's paper he thinks it will 

 tend to complicate rather than elucidate the subject. An account 

 of how Lagrange's original equations had i)een modified by 

 Hamilton, Routh, and himself is given at some length, and the 

 advantages and power of the mixed transformation, which he 

 had developed are pointed out. Prof. Henrici said he agreed 

 with Mr. Basset in preferring the more general method, but 

 thought the independent treatment of special problems as given 

 by Mr. Bryan and Dr. Burton, very desirable. —Dr. Burton in 

 reply said he concurred with Mr. Basset on some points, but 

 thought it decidedly advantageous to look at problems 

 from different points of view. The investigation he (Dr. 

 Burton) had given was applicable to any number of 

 solids, and on the whole simpler than Mr. Basset's. 

 The President pointed out that no attack had been made on 

 the validity or accuracy of Mr. Bryan's or Dr. Burton's work. 

 As to simplicity of the various methods, different opinions 

 might be expected to exist. He himself thought it very desirable 

 that such problems should be approached from different sides. — • 

 Prof. G. M. Minchin read a paper on the magnetic field of a 

 circular current. ^A paper on the differental equation of electric 

 flow, by Mr. T. H. Blakesley, was postponed. 



Royal Microscopical Society, February 15. — Mr. A. D. 

 Michael, President, in the chair.— Mr. E. M. Nelson 

 exhibited a microscope made by Messrs. Watson, to which 

 several novelties had been applied. — Mr. J. W. Lovibond read a 

 note on the measurement of direct light by means of the tinto- 

 meter. Mr. Nelson said that the wonderful results obtained by 

 the author by means of his instrument were perfectly surprising, 

 It was, in fact, equal to discovering differences down to mil- 

 lionths of a tint ; having had the pleasure of seeing and using 

 it he soon found that there was a very decided difference in the 

 colour sensation of his own eyes, which until that time he had 

 never suspected. It had done such marvels when applied 

 to macroscopic purposes that he did not doubt it 

 would do much also when applied to microscopic 

 studies. — Mr. G. S. Marriott's form of mounting and 

 dissecting s'and was exhibited and described by Mr. Nel- 

 son. — Mr. T. F. Smith read a paper on the use of mono- 

 chromatic yellow light in photomicrography. — Prof. F. J. Bell 

 read a letter from Dr. H. G. Piffard bearing on the same sub- 

 ject. — A paper descriptive of two species of rotifers by Mr. J. 

 Hood was also read by Prof. Bell. — Mr, Nelson read a paper 

 on the chromatic curves of microscope objectives. — Dr. W. H. 

 Dallinger said that Mr. Nelson was quite right in p linting out 

 that unless we could devise means for employing the shorter 

 wave-lengths of the spectrum we had approached very near to 

 the limits of visual possibility with the means at present at our 

 disposal. But as to the belief expressed by Mr. Nelson that 

 glass such as was useH in our objectives was not transparent to 

 the higher violet and ultra-violet rays, and to some extent also 

 to the blue, it must be remarked that there could be no doubt 

 but that the figures of the lenses had much to do with this ; it 

 led them up to the consideration of the question as to what 

 would be a suitable form and medium for lenses capable of 

 allowing the higher rays to be used. There could be little 

 doubt that all who believed in a future advantage in the use of 

 monochromatic light foresaw that there must be lenses specially 

 prepared for its use. They all knew now that they had reached | 



NO. T22I, VOL. 47] 



the limit of possibility so far as present materials were con- 

 cerned ; for if a lens could be made with a N. A. of 2 00, there 

 was no liquid medium to use with if, because no medium so 

 employed would be tolerant of living or even organic substances. 

 If, therefore, they could by some means use shortened wave- 

 lengths, they would have accomplished something extremely 

 useful. — The rest of the agenda was postponed in consequence 

 of the lateness of the hour. 



Entomological Society, March 8.— Capt. Elwes, President, 

 in the chair. — Herr Pastor Wallengren, of Farhult, bei Hciganas 

 Sweden, and Herr Hofrath Dr. Carl Brunner Von-Wattenwyl, 

 of Vienna, were elected Honorary Fellows of the Society to fill 

 the vacancies in the list of Honorary Fellows caused by the 

 death-; of Prof. Hermann C. C. Burmeisterand Dr. Carl August 

 Dohrn. — Dr. D. Sharp, F. R. S., exhibited a fine species of 

 Enoplolriipes from Slam, which was believed to be new, and 

 which he thought Mr. Lewis intended to describe under the 

 name of ^. principalis. This insect has great power of making 

 a noise, and the female seemed in this respect to surpass the 

 male. — Mr. W. F. H. Blandford said he wished to supplement 

 the remarks which he made at the meeting of the Society on 

 February 8 last, on the larva of Rhynchophortis. He stated that 

 he had since found that only the first seven pairs of abdominal 

 stigmata were rudimentary. The posterior pair were well 

 developed and displaced on to the dorsum of their segment, 

 which was thickly chitinised, and bore a deep depression, on the 

 margins of which the spiracles were situated. He added 

 that dissection showed that the posterior pair were the 

 principal agents of respiration. — Mr. W^. H. B. Fletcher 

 exhibited a long series of bred Zygana lonicem and Z. 

 trifolii, hybrids of the first generation with the following 

 parentage : — Z. lonicera, male— Z. trifolii, female ; Z. trifolii, 

 male — Z. lonicem, female ; also hybrids of tha second genera- 

 tion between Z. trifolii — hybrid, and Z. lonicera — hybrid. He 

 stated that many of the hybrids were larger than the parent 

 species, and that some hybrids between Z. lonicercE and Z. 

 JilipendulcE were the largest he had ever s-een. He added that 

 Zygana meliloli would not hybridise with Z. lonicerce, Z. trifolii 

 or Z. filipendiiliE. — Mr, F. W. Frohawk exhibited a bred 

 series of Vanessa alalanta, showing the amount of variation in 

 the red band on the fore wings of the female. — Capt. Elwes 

 exhibited a large number of specimens of Chrysophanus phlccas 

 from various places in Europe, Asia, and North America, with 

 the object of showing that the species is scarcely affected by 

 variations of temperature, which was contrary to the opinion 

 expressed by Mr. Merrifield in his recent paper on the effects 

 of temperature on colouring. Mr, McLachlan, F, R S., 

 Mr. A. J, Chitty, Mr. Bethune-Baker, Mr. Tutt, and iMr. 

 Barrett, took part in the discussion which ensued. — Dr. Sharp 

 read a paper entitled "On Stridulating Ants." He said that 

 examination revealed the existence in ants of the most perfect 

 stridulating or sound-producing organs yet discovered in insects, 

 which are situated on the 2nd and 3rd segments of the abdomen 

 of certain species. He was of opinion that the structures which 

 Sir John Lubbock thought might be stridulating organs in 

 Lasius Jiavus were not really such, but merely a portion of the 

 general sculpture of the surface. Dr. Sharp said that the sounds 

 produced were of the greatest delicacy, and Mr, Goss had been 

 in communication with Mr. W. H. Preece, F.R S., with the 

 view of ascertaining whether the microphone would assist the 

 human ear in the detection of sounds produced by ants. Mr. 

 Preece had staled that the microphone did not magnify, but 

 merely reproduced sound, and that the only sounds made by 

 ants which he had been able to delect by means of the instru- 

 ment were due to the mechanical disturbance produced by the 

 motion of the insects over the microphone. A long discussion 

 ensued, in which the President, Canon Fowler, and Messrs. Cham- 

 pion, McLachlan, Goss, Hampson, Barrett, Burns, and Jacoby, 

 took part. —Mr. C. J, Gahan read a paper entitled " Notes on 

 the Longicornia of Australia and Tasmania, Part I. ; including 

 a list of the species collected by Mr, J. J. Walker, R.N." 



Geological Society, March 8.— W. H. Hudleston, F.R.S., 

 President, in the chair. — The following communications were 

 read ; —On the occurrence of boulders and pebl>les from the glacial 

 drift in gravels s 'Ulh of the I hames, by Ilorace W. Monckton. 

 North of the Thames near London, the glacial drift consists 

 largely of gravel, which is characterised by an\ abundance of 

 pebbles of red quart^ite and boulders of quartz and igneous 



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