Dec. 21, 1871J 



NATURE 



155 



this communicalioii the author gave descriptions of all thefos^iIs 

 hitherto undesciibed from the !\Ienevian rocks of Wales. The 

 additions made to the fauna of the Lower Cambrian rocks (Long- 

 mynd and Menevian groups) by the author's researches in Wales 

 during the last few years now number about fifty species, belong- 

 ing to twenty-two genera, as follo^\s : — Trilobites, 10 genera and 

 30 species ; Bivalved and other Crustaceans, 3 genera and 4 

 species ; Brachiopods, 4 genera and 6 species ; Pteropods 3 genera 

 and 6 species ; Sponges, \ genus and 4 species ; Cystideans, I 

 genus and i species. By adding to these the Annelids, which are 

 plentiful also in these rocks, we get seven great groups repre- 

 sented in this fauna, the earliest known at present in this country. 

 By referring to the Tables published in M. Barrande's e.vcellent 

 new work on Trilobites, it will be seen that this country also has 

 produced a greater variety, or, rather, representatives of a greater 

 number of groups from these early rocks than any other country. 

 The species described included Agiiostiis, 5 species ; Arioitelhis, 

 I species ; Eriniiys, I species ; Holoccphalina, I species ; Cono- 

 coyyphc, 2 species ; Atiopolcmis, 2 species ; Cyrtotheca, I species ; 

 Stenotlicca, I species ; Theca, 2 species ; Protocystitis, i species, 

 &C. The author also entered into a consideration of the range of 

 the genera and species in these early rocks, and showed that, with 

 the exception of tlie Brachiopods, Sponges, and the smaller Crus- 

 tacea, the range was very limited. A description of the various 

 beds forming the Cambrian rocks of St. David's was also given, 

 and proofs adduced to sliow that frequent oscillations of the sea- 

 bottom took place at this early period, and that the barrenness of 

 some portions of the strata, and the richness of other parts, were 

 mainly attributable to these frequent changes. Mr. Gwyn Jef- 

 freys suggested that the term Polyzoa might be adopted in pre- 

 ference to that of BryoEoa, as being the more ancient ter.Ti, and 

 that the name Proserpina should not be applied to the new genus 

 of Trilobites, as it had already been appropriated to a tropical 

 form of land-shell. 



Royal Geographical Society, December 11. — Major-Gen. 

 Sir H. C. Rawlinson, president, in the chair. — A paper was 

 read by Mr. Keith Johnston, " On the Rev. Thomas Wake- 

 field's ilap of Eastern Africa ; '' the subject being limited to the 

 form of Speke's Lake Victoria Nyanza, which Wakefield's native 

 travellers had decided to consist of at least two lakes. — Capt. 

 R. F. Burton followed with a paper on " Lake Ukara or Uka- 

 rewe, " in which he argued from the new information gleaned by 

 Mr. W.ikefield at Mombaz, and Captain Spe'ice's own data, that 

 Victoria Nyanza consisted of many separate lakes, and that it 

 was a " Lake Region," and not a single lake. 



Sunday Lecture Society, December 17. — "On the 

 Optical Construction of the Eye," by Dr. Dudgeon. The 

 early part of the lecture was occupied with a description of 

 the optical construction of the eye. In order to ascertain 

 the precise focal length of aqueous humour, the lecturer 

 immersed his eyes in water, which, being of the same refrac- 

 tive power as the aqueous humour, extinguishes it as a lens. 

 He then ascertained what power of lens was required to restore 

 perfect vision under water, which lie found to be affected by an 

 artificial lens, whose focus was exactly i.V inch under water. He 

 constructed a pair of spectacles fitted with air lenses, formed by 

 very concave watch-glasses placed back to back, and united round 

 their edges by a ring of wood or vulcanite. In this way he 

 formed air lenses which had a focus of i \ inch in water, but 

 which oflered no obstruction to vision in the air. ^Vith these 

 spectacles perfect vision both for near and distant objects below 

 the water was obtained, and on coming to the surface these spec- 

 tacles allowed of perfect vision in the air. He then explained 

 the construction of the eyes of fishes and amphibia, which have 

 no anterior aqueous lens, but only a nearly spherical crystalline 

 lens. He next explained the mechanism of the accommodation 

 of the eye from distant to near vision. He showed that this was 

 not effected by any increase of the convexity of the anterior 

 surface of the crystalline lens, as is generally supposed, but by a 

 slight rotation of the crystalline lens from without inwards, 

 whereby the focus of the crystalline lens was shortened to the 

 degi-ee necessary to throw the image of a near object accurately 

 on the retina. Finally, he pointed out that some of the principal 

 discoveries of modern physicists already existed in the eye. Thus, 

 the principle of achromatic lenses by the combination of two 

 lenses of different refractive power was seen in the eye when a 

 water lens was combined wi'h the crystalline lens ; the discovery 

 of Descartes, that an ellipiical surface of a lens obviated 

 spherical aberration, was also found in the eye ; and Herschel's 

 discovery that a combination of the meniscus with the double 



convex lens prevented spherical aberration also obtained in the 

 eye. 



Photographic Society, Decemberl2. — A paper was read by 

 Lieut. Abney, R.E., F.R.A.S., on albumen applied to photo- 

 graphy. He first referred to the use of albumen as a substratum 

 for collodion films. Taking different ]5roportions of albumen 

 and water, and iodising part of each, he found that with the best 

 collodion process the iodised substratum as a whole gave neither 

 increase nor dim.inution of sensitiveness, whilst with the uniodised 

 substratum the sensitiveness was slightly diminished. He next 

 pointed out the cau?e of blisters in developing dry plates, and 

 traced them to the expansion of the albumen ; the substratum 

 rising from the glass at the smoother portions. He lastly touched 

 upon the uncombined sulphur always present in albumen, as 

 much as i '2 grains being found in a whole sheet of paper, whilst 

 but J grain of metallic silver was found in prints of the same 

 area. He argued from this that silver prints must fade, apart 

 from the imperfect washing, unless the sulphur be removed. He 

 recommended the makers of albumenised paper to try to do this, 

 first forming albumenate of potash by the addition of potash to 

 the albumen. The unprecipitated part contained the sulphur. 

 This might be removed and the albumen once more dissolved by 

 the addition of acid — A paper on M. Dagrou's microphotographic 

 despatches was also read, detailing the methods of preparation ; 

 as many as 50,000 messages were received in Paris during the 

 Siege upon these films, conveyed to the capital by pigeons. 



Manxhester 

 Literary and Philosophical Society, November 14. — E. 

 W. Binney, F. R. S. , president, in the chair. The president said 

 tliat, on Friday the loth inst., he observed at Douglas in the Isle 

 of Man, a splendid display of the aurora borealis. At S r. M. it 

 appeared as an arch of a greenish colour, extending from west to 

 east, through the tail of the Great Bear. Afterwards, at ten 

 o'clock, the same kind of arch was observed with another higher 

 up, which ranged west and east through the Pole star. At this 

 time numerous streamers and flashes of light of a green and 

 yellowish-white colour flashed up from near the horizon to the 

 zenith, from east, south, and west ; those towards the west had 

 a reddish hue. The sky was beautifully clear, and the light from 

 the aurora was greater than ever previously observed by him. — 

 " On the Origin of our Domestic Breeds of Cattle," by William 

 Boyd Dawkins, F.R.S. There are at the present time 

 three well-marked forms inhabiting Great Britain. i. The 

 hornless cattle, which have lost the horns which their 

 ancestors possessed through the selection of the breedei". The 

 polled Galloway cattle, for instance, are the result of the care 

 taken by the grandfather of the present Earl of Selkirk, in only 

 breeding from bulls with the shortest horns. The hornless is 

 altogether an artificial form, and may be developed in any breed. 

 2. The Bos lougifrous, or the small black or dark brown Welsh 

 and Scotch cattle, which are remarkable for their short horns 

 and the delicacy of their build. 3. The red and white variegated 

 cattle, descended from the urus, and which have on the whole 

 far larger horns. These two breed freely together, and conse- 

 quently it is difhcuU to refer some strains to their exact parentage. 

 The large domestic cattle of the urus type are represented in 

 their ancitnt purity by the Chillingham wild oxen, as they are 

 generally termed, but the exact agreement of their colour with that 

 specified in the laws of Howel Dha proves that they are descended 

 from an ancient cream-coloured domestic ox with red ears. 

 The animal was introduced by the English invaders of Roman 

 Britain, and was unknown in our country during the Roman 

 occupation. The Bos longifrons, on the other hand, was the 

 sole ox which was domestic in Britain during the Roman occu- 

 pation, and in the remote times out of the reach of history it 

 was kept in herds by the users of bronze, and before that by the 

 users of polished stone. This is proved conclusively by the ac- 

 cumulations of bones in the dwelling-places and the tombs of 

 those long- forgotten races of men. The present distribution of 

 the two breeds agrees almost exactly with the areas occupied by 

 the Celtic population and the German or Teutonic invaders. 

 The larger or domestic urus extends throughout the low and 

 fertile country, and indeed through all the regions which were 

 occupied by Angle, Jute, Saxon, or Dane; while the smaller 

 Bos totigtfrotis is to be found only in those broken and ragged 

 regions in which the unhappy Roman provincials were able to 

 make a stand against their ruthless enemies. The distribution, 

 therefore, of the two animals corroborates the truth of the view 

 taken by Mr. Freeman, that the conquest of Britain by the 



