Nov. 8, 1883] 



NA TURE 



29 



observe and calculate in both" systems the same large lot of 

 angles. It was then found that the use of decimals gave a saving 

 of two-sevenths of time either in observation or in calculation. 

 This result was unknown to Sir George Airy, the ablest astrono- 

 mer of our time, but he judged rightly that the conver>ion of all 

 sexagesimal angles into decimal ones would materially lighten 

 his labours, and he actually did so when calculating all the lunar 

 observations previously made at Greenuich. This was the 

 largest quantity of reductions ever made by one astronomer, and 

 they were abridged by the use of decimals. The real supporter 

 of sexagesimal divisions is routine, that sly enemy of progress. 

 Abbadia, November 2 An'TOINE d'Abbadie 



Christian Conrad Sprengel 



It has now become a standing topic that C. C. Sprengel's 

 treatise on the structure and fertilisation of flowers "after well 

 nigh a century of oblivion has come to be recognised as one of 

 the most interesting books, and his theory of the adaptation of 

 flowers to fertilisation by insects is one that will ever be asso- 

 ciated with his name" (Nature, vol. xxviii. p. 513). Some 

 writers go so far as to speak of a rediscovery of Sprengel's 

 treatise by Darwin. But it should be acknowledged that Darwin 

 himself says only ("Cross Fertilisation," p. 5): "Ilis disco- 

 veries were for a long time neglected." So it seems to be true 

 that Sprengel's and Koelreuter's works were unknown to Eng- 

 lish naturalists, though Kirby and S pence, at the end of Letter 

 IX., published 1815, and in all subsequent editi ms till 1867, 

 have given a very fair report in their masterly manner. Not 

 only the facts, but also the importance of these discoveries, are 

 fairly expounded. 



In Germany these discoveries were well known to every 

 naturalist during the whole century. In 1829, when a mere boy, 

 my father began to instruct me in entomology. Many times he 

 took Sprengel's work from the shelves in his study, and explained 

 to me the discovery of fertilisation of plants by insects with the help 

 of the plates in Sprengel's book. I have never forgotten the in- 

 terest and the scientific enthusiasm of his exposition. I was told 

 that we are indebted to a mere chance for this discovery. A rather 

 dangerous irritation of Sprengel's eyes had the residt that he 

 was entirely forbidden indoor .study by his physician, and was 

 therefore obliged to spend his days m the field, where he was 

 gradually led to the observation of plants, followed by his re- 

 markable discoveries. Certainly between 1S30 to 1S40 at every 

 university in Prussia the same facts were taught as well known 

 facts of the highest importance, and of course known by every 

 student. Prof. C. F. Burdach has related them in his large 

 " Physiology," vol. i. p. 322, 1826, and given his conclnsions. 

 H. Burmeister, " Handb. d. Entomologie," vol. i. p. 303, 1832, 

 speaks about them at some length also as well known and of the 

 highest importance. Not only scientific publications, but merely 

 popular works have the same statements. Pierer's " Universal 

 Lexicon " (first edit. 1S36, fourth, 1851, vol. ix. p. 942) gives a 

 fair report. H. A. Hagen 



Cambridge, Mass., October 23 



"Challenger" Zoological Reports 



It seems to me that the reviewer of my Report on the Pelagic 

 Hemiptera collected during the voyage of the Challenger 

 (Nature, vol. xxix. p. 3) is too hypercritical. 



I refer, of course, to the paragraph in which he blames me for 

 alluling to species under their trivial names only ; and as the 

 paragraph in question is calculated to convey a wrong impres- 

 sion, I should be obliged if you will kindly allow me to say a 

 word on the subject. 



It is true that some writers upon insects (or rather upon 

 Lepidoptera only) have the very bad habit of alluding to species 

 (of different genera) by their specific names only, and the law 

 that forbids the practice is a good one ; but it may be applied 

 too stringently, and not altogether in the sense that its framers 

 intended. 



In my Report I had to deal with two genera, and a reader of 

 the review who had not seen the Report itself would be justified 

 in concluding from the words of the reviewer that I have used 

 the specific names indiscriminately, without indicating the genus 

 to which the species belonged. In point of fact this is not the 

 case. The two genera are treated of separately, and where I 

 have mentioned I he trivial without the generic name, it has only 

 been when the generic name governed the paragraph, and, when, 



consequently, no doubt could possibly exist as to the genus. In 

 doing so I may have broken the hihr of the law, but not, I 

 think, the spirit : and were the work to be done over again, I 

 think I would be inclined to follow the same course. 



F. Buchanan White 



[The idea of a generic term governing a paragraph did not 

 strike me. I had no wish to be over-critical, and I am glad to 

 find that in all essentials Dr. Buchanan White agrees with the 

 views expressed. — The Writer of the Notice.] 



Barytes from Chirbury 



A number of crystals of barytes have lately been acquired by 

 Mr. Henson from Chirbury, Salop, which seem to deserve some 

 description. The crystals vary from one to four inches in length 

 and from one-half to two inches in breadth ; they are very bright 

 and clear, and are elongated in the direction of the brachy- 

 diagonal, resembling in appearance the barytes from Dufton ; 

 they are mostly doubly terminated, and some contain included 

 crystals of copper pyrites. They were at once detected by Mr. 

 T. Davies as being peculiar in form ; and the reflecting gonio- 

 meter revealed the existence upon them of four very well-defined 

 forms v\ hich have not been hitherto found upon barytes, besides 

 two more doubtful planes to which it is difficult to assign definite 

 symbols. 



The crystals are almost all a combination of the forms — 



[loij Vw 

 a'|oiz} iPoo 

 m [lioj. M P 

 / ',0141 .jPoo 

 Poo 



tool 00 Poo 



E (412} 



y {212] 



= {:„} 



i [232; 



a> {432) 



2P4 

 I>2 

 P 



m 

 2H 



b {010} 00 Poo 



c 5.001] oP 



On some crystals were also observed- - 



;u (214) 4P2 between (/and 

 r (112) JP between (/and j)/ 

 Z (034) I Poo between u and d. 



The general appearance of the crystals is shown in the annexed 

 gure. 

 Of the above faces |, 01, E, and Z are new. i, lies with parallel 



edges between the faces dm and a/', and is very dull : w lies 

 between y »i and : 0' ; E between y a and z. 



Several of these crystals have also a small dnll face Q lying 

 with parallel edges between and y, and on one this is accom- 

 panied by another small dull face V between and m. By 

 oiling these faces it was possible to determine approximately 

 their inclination to 0. The measurements lead to the complicated 

 symbols (15. 1. 15) for Q and (19. 1. tS) for Y. 



The new faces, and especially E, are very characteristic of 

 these specimens, and it is somewhat curious that faces with the 

 simple symbols of {, w, £, Z, have not hitherto been noticed 

 among the sixty-six recorded forms of barytes. 



H. A. MiERS 



Mineral Department, British Museum, October 25 



