f 



April lO, 1879"] 



NATURE 



527 



Delegacy caused it to be undertaken ; to Mr. Bell, who 



seems to have very efficiently performed the actual task 

 of translation ; ^ to Mr. Garrod for the Appendix already 

 mentioned ; and last, though not least, to Prof. Peters for 

 supplying the use of the very plates which illustrated 

 Miiller's work. 



OUR BOOK SHELF 



Proceedings of the London Mathematical Society, vol. ix. 

 (November, 1877, to November, 1878,) 279 pp. 

 (Hodgson and Son, Gough Square, 1879.) 



We have, in previous notices, indicated the character of 

 the papers contained in former volumes, and the same 

 remarks apply equally well to the volume before us. We 

 shall content ourselves, in our present notice, with giving 

 the titles and author's names only of the more important 

 papers. 



Prof. Cayley, not so large a contributor as usual, 

 furnishes a short paper " On the Geometrical Represen- 

 tation of Imaginary Quantities, and the Real(»«, «) Corre- 

 spondence of Two Planes," and another equally short, 

 " On the Theory of Groups." There are brief notes " On 

 a Generalised Form of Certain Series," by Mr. Glaisher ; 

 "On the Transformation of Elliptic Functions," by Dr. 

 Klein, of Munich ; " On Certain Extensions of Frullani's 

 Theorem," by Mr. C. Leudesdorf; "The Flexure of 

 Spaces," by Mr. C. J. Monro; ''On the Relation 

 between the Functions of Laplace and Bessel," by 

 Lord Rayleigh ; "Notes on Normals," and "The 

 Decomposition of Certain Numbers into Sums of Two 

 Square Integers by Continued Fractions," by Mr. S. 

 Roberts. Longer papers are : " On the Singularities of 

 the Modular Equations and Curves," by Prof H, J. S. 

 Smith ; "On Partial Differential Equations with Several 

 Dependent Variables," and "On a General Method of 

 Solving Partial Differential Equations," by Prof Lloyd 

 Tanner; "A Method in the Analysis of Plane Curves," 

 by Mr. J. J. Walker; "On Conjugate Four-piece 

 Linkages," by Mr. A. B. Kempe ; and " A New 

 Method of finding Differential Resolvents of Algebraical 

 Equations," by Mr. R. Rawson. M. Halphen contri- 

 butes a long and valuable paper on " The Characteristics 

 of Systems of Conies." 



Physical papers are " On the Electrical Capacity of a 

 Long Narrow Cyhnder, and of a Disk of Sensible Thick- 

 ness," by Prof. J. Clerk Maxwell ; " On the Conditions 

 for Steady Motion of a Fluid," by Prof Lamb; "Notes 

 on the Solution of Statical Problems connected with 

 Linkages and other Plane Mechanisms," by Prof. A. B. W. 

 Kennedy; "On the Astatic Conditions of a Body acted 

 on by given Forces," by Prof Minchin; and "Progres- 

 sive Waves," by Lord Rayleigh. Mr. H. McCoU con- 

 tributes a paper in two parts bearing on logic and proba- 

 bilities, viz., "The Calculus of Equivalent Statements." 



LETTERS TO THE EDITOR 



[ The Editor does not hold himself responsible for opinions expressed 

 by his correspondents. Neither can he undertake to return, or 

 to correspond with the -writers of, rejected manuscripts. No 

 notice is taken of anonymous communications. 



[ The Editor urgently requests correspondents to keep their letters as 

 short as possible, ITu pressure on his space is so great that it 

 is impossible otherwise to ensure the appearatue even of com- 

 munications containing interesting and navel facts.l 



Brorsen's Comet 



I OBSERVED Brorsen's comet, about 8h. on March 29, through 

 a whitish haze that extinguished the small stars near it. It 

 appeared about the seventh magnitude, by estimation 3' in 



' We might take exception, perhaps, to his rendering of the title, which, 

 we think, might have been mjre literally and better expressed by '* Or. the 

 Hitherto Unknown Diversities of Type in the Singing Organs," Sac. 



diameter, its light very much condensed in the centre and ap- 

 proximately circular. 



On Apnl 4 I obtained the following places, although the 

 moonlight much diminished its brilliancy : — 



1874. G.M.T. App. R.A. App. decl. 



h. m. s. h. m. s. o ' /« 



April 4 ... 8 29 59 ... 2 56 537 ... + 25 42 36 

 „ ... 8 38 31 ... 2 56 55*3 ... + 25 42 56 



At the first observation the comet was compared with the star 

 Arg. -1- 25°, No. 485 ; at the second with Arg. + 2$°, No. 496 

 (Bonn Obs., vol. vi.). The observations admit of more acciu-ate 

 reduction. 



The correction to the ephemeris of Herr Schuke (reproduced 

 in Natxtre, vol. xix. p. 510) is — 



In R.A. 



- 5'o I in decl -31 20 



On both evenings when the equatorial was set to the position 

 given in the ephemeris (with Stras-er's correction, A.N. 2250) 

 the comet was not in the field of a low power. The above cor- 

 rection to the declination may prevent loss of time in finding the 

 comet. G. L. Tupman 



I, Vanbrugh Park, Blackheath, April 6 



Madagascar Forms in Africa 



A PARAGRAPH in a recent number of Nature (p. 470) men- 

 tions the discovery of a new species of Ouvirandra in Eastern 

 Africa, the genus being hitherto supposed to be peculiar to 

 Madagascar. The plant in question, which was collected by 

 Dr. Hildebrandt, is, however, as has been pointed out by Dr. 

 Trimen and myself (Gardeners' Chronicle, February i, p. 149), 

 not a species of Ouvirandra, being destitute of the fenestrated 

 leaves, which is the only distinguishing character of that not very 

 sound genus. It is, in fact, a well-known and widely-distributed 

 African plant, Aponogeton leptostachyus, E. Mey. Dr. Hilde- 

 brandt, when lately in this country, fully assented to this identi- 

 fication. 



A more novel fact in the same connection is the discovery by 

 my colleague. Prof. Oliver, of a ne%v monimiaceous plant amongst 

 the collections of Gustav Mann in East Tropical Africa. The order 

 itself, though represented in Tropical America and Asia, has 

 hitherto been unknown in Africa, although the Mascarene Archi- 

 pelago is w ell supplied w ith species, and one at least is known 

 from the Comoro Islands, whence its remarkable fruit was sent 

 to the Kew Museum by Dr. Kirk. 



W. T. Thiselton Dyer 



Transportation of Seeds 



In Nature, vol. xvii. p. 390, which through the careless- 

 ness of my agent has only just reached my hands (together with 

 the numbers for August, September, October, and part of 

 November), I see Mr. Francis Darwin notices the penetration 

 of certain grass seeds through the skin of sheep. It may in- 

 terest him and your readers to know that I can corroborate this 

 from what I have witnessed here and at the Cape of Good 

 Hope. 



In passing a butcher's shop in Noirmea, lately, I was struck 

 with the appearance of a fore-quarter of mutton. On a closer 

 examination I found it so full of grass- seeds that it resembled 

 a ham just unpacked from its bag of chaff". Many of the seeds 

 had still their long thin tails drawn through the flesh like 

 threads interlacing each other in every direction. On question- 

 ing the butcher, he said they rarely kUled a sheep that was not 

 more or less punctm-ed. 



All our sheep are imported for slaughter from Australia or 

 Norfolk Island. This particidar one came from the former 

 place. 



At the Cape of Good Hope I have skinned "spring-bucks," 

 in which the shanks were pierced through and through with 

 these "awms" and small thorns. My wonder has been how 

 the animals could endure the pain of moving, but I suppose 

 they do not suffer as we do. E. L. Layard 



British Consulate, Noumea, New Caledonia, February i 



Rayons de Crepuscule 



What does Mr. Abbay call (vol. xviii, p. 540), the "low 

 country " in Ceylon ? If he means the sea-board generally, I 



