November 2, 191 1] 



NATURE 



continental area by the Cambrian marine transgression. 

 Their ancestors are thus to be looked for beneath the 

 existing oceans. The fossils now known from the 

 American Algonkian may have been of fresh or brackish 

 water types ; littoral forms were occasionally imported 

 among them from the series continuously developing in the 

 seas. Walcott's studies of the Cambrian faunas of China 

 are continued, with illustrations of new species of trilobites 

 (vol. Ivii., No. 4). Evidence is given {ibid., No. 3) that 

 certain me,dusiform fossils from the Middle Cambrian of 

 British Columbia are in reality holothurians, being charac- 

 terised by a large spiral alimentary canal. The descriptions 

 and illustrations of these forms possess great interest for 

 ail workers among Older Palaeozoic strata. 



G. A. J. C. 



STEREOSCOPIC VISION AND INSTRUMENTS. 



Y^/E have received a copy of a brochure entitled " Stereo- 

 * * skopisches Sehen und Messen " (pp. 40, price i mark), 

 by Carl Pulfrich. This is the German version, or rather 

 original, of the article " Stereoscope " in the recent new 

 edition of the " Encyclopiedia Britannica." A little more 

 detail is given here and there in the German pamphlet 

 than in the " Encyclopaedia " article, and the former con- 

 cludes with a very useful bibliography of papers published 

 in the present century relating to binocular vision, which 

 is not given in the " Encyclopaedia." This is to be taken 

 as supplementary to the bibliography in von Rohr's well- 

 known work " Die binokularen Instruniente " (see Supple- 

 ment to Nature, March 5, 1908) of memoirs published up 

 to 1900. 



The pamphlet gives a concise, but clear and interest- 

 ing, account of the more important points in the theory 

 of stereoscopic vision ; but its main value lies in the 

 brief description which follows of the important modern 

 developments and applications of stereoscopic methods, to 

 which the author has himself so largely contributed. Not 

 the least interesting among these are the well-known stereo- 

 comparator and the so-called " blink " microscope, the 

 latter of which has proved so valuable in the detection of 

 new planets and variable stars. We think it is desirable 

 that attention should be drawn to the very imperfect, not 

 to say unintelligible, translation of Pulfrich 's text which 

 constitutes the article in the " Encyclopaedia Britannica " 

 above referred to. It is surprising that both translator and 

 editor should have allowed passages to pass which are so 

 far astraj' from the original. Thus we read : " The reason 

 for this [double images] is that when P (or H') is fixed, 

 the images of H' (or P) are always separated from one 

 another by the centre of the yellow spot." Fixed should 

 be " focussed " (no doubt " fixiert," but the original is 

 here paraphrased). Again : " The power of perception of 

 depth in man is most accurate. This has been ascertained 

 by the approximately equal keenness of vision of all normal- 

 sighted people and by the interpupillary distance." This 

 is quite incomprehensible until one learns that the words 

 in italics (ours) are a perversion of " Es wird bestimmt." 

 "Parallax" (Parallaxe) appears as "parallel axis." 



It is impossible briefly to convey an idea of the confusion 

 in the mind of the reader caused by numerous errors of this 

 description ; but we would strongly recommend all those 

 interested in the subject-matter of the article to refer to 

 Pulfrich 's German memoir. 



THE TECHNICAL COLLEGE, BRADFORD. 



A N important extension of the buildings of the Bradford 

 Technical College was opened by Lord Rotherham 

 on October 25. The extension takes the form of a model 

 experimental mill, in which all processes involved in the 

 production of woollen and worsted cloth, from the raw 

 material to the finished article, can be carried out on a 

 practical scale. The building comprises a three-storey 

 front block 175 feet long, devoted to lecture-rooms, textile 

 testing-room, museum, experimental rooms, &c. Behind 

 this are two large sheds, each 90 feet by 70 feet, one con- 

 taining the combing, carding, and spinning machinery, and 

 the other the looms. The equipment for the production of 

 yarns of various types is very complete, consisting of Pre- 

 pnring Box, Worsted Carding Engine, Noble Comb, French 



\(>. 2192, VOL. 88] 



Comb, French, Cone, and Open Drawing Sets, Flyer, Cap 

 and Ring Spinning Frames. In a separate shed are warp- 

 ing mills and dressing frames, while the power looms 

 include examples of all types. The wool-washing room con- 

 tains three bowls of a total length of about 80 feet. The 

 practical dyehouse and finishing rooms each have an area 

 of about 300 square yards, and are equipped with full- 

 size machines for the treatment of loose wool, slubbing, 

 yarns, and piece goods. 



A detached building houses the power plant, which 

 includes a 30 foot by 8 foot boiler, with superheater, 

 economiser, &c. The engine-house contains four prime 

 movers, a suction gas engine of 125 horse-power, a slow- 

 speed cross-compound engine of 200 horse-power, a high- 

 speed inverted vertical engine of 75 horse-power, and a 

 steam turbine of about the same power. Each of the 

 three engines drives a direct-current generator, while the 

 turbine is coupled to a three-phase alternator. Both 

 engine- and boiler-houses are fitted with a complete set of 

 testing apparatus ; but while primarily intended for educa- 

 tional work, the power plant will provide light and elec- 

 trically transmitted power for three large buildings — the 

 main college block, the extension, and the school of art. 



The new buildings have been erected at the cost of about 

 20,oooZ., and for the equipment an additional sum of about 

 14,000/. has been provided, which sum would have been 

 much increased but for the generosity of most of the 

 machine makers, who have supplied the equipment on very 

 favourable terms. Much of the machinery throughout the 

 building has been specially designed, so that while of a 

 thoroughly practical character, experimental work not 

 possible in a mill can be carried out. 



ZOOLOGY AT THE BRITISH ASSOCIATION.' 

 C ECTION D presented a full and varied programme, 

 '-^ and the attendance at the several sessions was above 

 the average of recent meetings. This meeting was un- 

 doubtedly one of the best of recent years. 



As in previous years, there were two lectures of a semi- 

 popular character, which were highly appreciated. Mr. 

 Fred Enock lectured on the " fairy flies " (Mymarid^), 

 hymenopterous insects of small size and with peculiar 

 delicate wings, without veins, but fringed with long hairs. 

 Mr. Enock, who has devoted many years to the study of 

 this family, illustrated his account by means of a beautiful 

 series of original drawings, shown by the lantern. He 

 described the principal characters of the male and female, 

 and traced the life-history of Anagrus incarnatus, the eggs 

 of which are laid in the egg of the frog-hopper. 



In his lecture on the fossil reptiles of the Oxford Clay 

 of Peterborough, Dr. C. W. Andrews gave an account of 

 the remarkable assemblage of reptiles occurring in that 

 deposit. The beds in which the remains were found are 

 of Middle Jurassic age, and were probably laid down not 

 far from land and near the mouth of a large river. The 

 horizon at which the remains occur is that characterised 

 by ammonites of the " ornate " group, Cosmoceras 

 gtilielmi being a common species. Among the remains are 

 those of land reptiles carried down by the river and oi 

 many marine forms of several distinct orders. Cetio- 

 saurus, a terrestrial dinosaur allied to Diplodocus, attained 

 a length of 60 feet, the greater part being made up of the 

 greatly elongated neck and tail. Another, but smaller, 

 dinosaur, Stegosaurus, and a pterodactyl, Rhampho- 

 rhynchus, were also found. The marine reptiles were more 

 numerous, and of astonishing variety of form ; for instance, 

 ichthyosaurs, plesiosaurs of many types, and numerous 

 marine crocodiles of the genera Metriorhynchus and Steno- 

 saurus. The ichthyosaur Ophthalmosaurus was remark- 

 able for the fact that in the adult the teeth were extremely 

 small, and in some cases perhaps absent, so that the food 

 of this animal must have been very different from that of 

 its relatives. In many cases the skeletons were found in a 

 nearly complete condition ; in others the carcases seem to 

 have been torn to pieces by predaceous reptiles, the bones 

 being deeply Scored by their teeth. Dr. Andrews exhibited 

 a series of lantern-slides showing the actual remains and 

 reconstructions based upon these. He stated that the 



1 "Some Rerent Work on .Sex " nnci an acconnt of the discussion on the 

 origin of mammals will form tlie subject of separate no'.ices. 



