May 12, 1892] 



NATURE 



45 



wire of an oil induction coil. The frequence of alternation 

 amounted to no less than 1,000,000 a second, while the electro- 

 motive force reached the enormous amount of 100,000 volts. 

 I'erhaps it was as well that this frequency was great, otherwise 

 the physiological action might have been rather surprising to 

 those who trusted implicitly in Mr. Crookes. The resistance 

 offered by the sheet of vulcanite to the strong current produced 

 some fine flashes, while very pretty were the examples of brush 

 discharges, St. Elmo's fires, &c., at the secondary poles of the 

 oil induction coil. 



The electrical apparatus shown by Captain Holden, R.A., 

 consisted of some very important new instruments, among which 

 we may mention the high-speed chronographic pen for taking a 

 number of successive records of short intervals of time, the pen 

 being automatically reset after each record ; an improved simple 

 compensated voltmeter on the hot wire system, and the dead-beat 

 alternating current ammeter worked by a heated metal strip and 

 free from self-induction. 



Prof. Roberts-Austen exhibited a new electrical method for 

 the exact determination of very high temperatures, which has 

 rendered possible the construction of a very simple instrument, 

 devised by Prof H. Le Chatelier, that can be placed in the hands 

 of any workman. The latter depends on the comparison of the 

 intensity of the radiation emitted by a glowing body (the tempera- 

 ture of which has to be determined) with that of a standard 

 source of light. To use the instrument it is pointed in such a 

 direction as to have the light from the heated mass of metal in 

 its field of view, so that the colour can be distinctly observed ; 

 in the same field of view a series of standard colours can also be 

 made apparent (situated side by side with the heated metal), by 

 turning a milled head screw which carries a pointer over a 

 graduated scale. By matching the colours a direct reading of 

 the position of the pointer gives the required temperature. 



The Rev. F. J. Smith exhibited an electric tram chronograph 

 which he had devised for measuring small periods of time, 

 varying from one-fourth to one-twenty-thousanth part of a 

 second. This instrument consists of a metal girder furnished 

 with a T-shaped end, carries two steel rails, and is supported on 

 a V-groove, hole, and plane system. The carriage, on which is 

 fixed a slightly smoked glass plate, runs on these rails, driven 

 either hy a weight or by a coiled spring. A metal pillar, carried 

 on a V-groove, hole, and plane system, is placed in front of the 

 moving surface, and supports electro-magnetic styli which can be 

 brought into contact with the smoked surface ; a tuning-fork 

 also is so placed that the traces are found to be recorded on the 

 smoked plate so as to afford a means of measuring the time 

 intervals. The two motions of the pillar, of rotation and vertical 

 translation, allow a large number of observations to be made on 

 the same plate. There are also continuous contact-breakers, 

 whereby, when a photographic plate is fixed in the carriage, 

 spark photographs of moving objects may be obtained. This 

 instrument has been applied to the measurement of the velocity 

 of projectiles, andjsmall periods of time in physiological research, 

 and to the photography of insects and falling drops of 

 liquids. 



Perhaps the most unique exhibit of the evening was the series 

 of photographs of flying-bullets which Mr. Boys had obtained 

 by a modification of an old method. The photographs showed 

 beautifully the waves in the air caused by the rapid flight of the 

 bullet analogous to those produced by a fast-going steamer. 

 In one slide the small pieces of paper through which the bullet 

 had passed were also seen ploughing their way through the air, 

 producing quite as definite waves as the projectile itself, only of 

 not such large dimensions. The passage of a bullet through a 

 piece of wire was also very curious, the piece of wire that was 

 cut off not having time to fall before it was seized by the light- 

 ning eye of the camera. The photograph showing a magazine 

 rifle bullet piercing a glass plate brought out some very interest- 

 ing facts. The glass appeared to be thoroughly scattered in a 

 direction opposite to that in which the bullet was proceeding, 

 the greatest scattering taking place on the side which the 

 projectile touched first. The waves set up on the glass plate 

 gave measures of the wave, length of the tremor caused, and the 

 velocity of travel. The bullets used for these pictures were of 

 various kinds, and the velocities varied from 750 to as much 

 as 3000 feet per second, the former from a pistol and the latter 

 from a magazine rifle, the bullet being composed of aluminium 

 to obtain this great velocity. 



The Committee of the Kew Observatory exhibited a testing 

 camera for photographic objectives that had been designed by 



NO. 1176, VOL. 46] 



Major L. Darwin. With this instrument all the most important 

 features of a lens can be accurately and swiftly determined. We 

 may mention here that arrangements are being made that any 

 lens sent to them will be thoroughly examined in all respects 

 under the superintendence of Mr. G. M. Whipple, certificates 

 of examination being made out, as is at present done in the case 

 of other instruments. 



We must now pass on to the photographs. 

 Astronomy was well to the fore with the exhibits of Messrs. 

 Lockyer and Roberts. The former showed a fine spectrum of 

 Nova Aurigas, that had been enlarged twenty- five times from a 

 negative taken with only a 6-inch object-glass and prism by the 

 Brothers Henry and Hilger respectively; several fine photographs 

 of stellar spectra illustrating the main evolutionary types accord- 

 ing to the metftoritic hypothesis, and photographs of the 3-foot 

 reflector at Kensington that is now near completion. Mr. 

 Roberts showed some photographs of celestial objects ; the 

 original negative of Nova Cygni, taken with a 20-inch reflector 

 with a two- hours' exposure, showing the Nova as a star of the 

 thirteenth magnitude. An enlargement of the region in which 

 Nova Aurigse was situated when the star was of the fourth 

 magnitude was also displayed, together with the original photo- 

 graph taken with the instrument before mentioned, but with an 

 exposure of three hours. 



The photographs showing the great sun-spot of February last, 

 exhibited by the Solar Ph)sics Committee, may be said to be 

 the best series that has ever been obtained. The series included 

 nine days, and showed the remarkable changes that occurred 

 during the interval from February 5 to February 17, 



Mr. W. Saville-Kent exhibited a series of photographs, over a 

 hundred, taken by himself, enlargements of the same, and water- 

 colour sketches, illustrating coral reefs, coral animals, and the 

 marine fauna generally of the Great Barrier district of Australia. 

 A lantern exhibition illustrating the same subject was also 

 included in the evening's programme. The reef views, which 

 portrayed extensive areas of growing corals of innumerable 

 varieties, were, as explained by the exhibitor, taken at abnor- 

 mally low spring tides, and are as a matter of fact very rarely 

 visible to the extent depicted. Among the more important 

 points associated with this exhibit were the facts that in a large 

 number of instances accurate measurements had be en taken of 

 the individual corals that compos ed the reefs photographed, 

 such reefs being in easily accessible positions, where their sub- 

 sequent amount and rate of growth could be periodically deter- 

 mined. This exhibit, more particularly with relation to the 

 illustrations of living coral polyps — those of the mushroom 

 corals, genus Fungia, being particularly noteworthy — represented 

 the first occasion in which photography has been systematically 

 applied to this highly interesting biological subject. A second 

 novelty exhibited by Mr. Saville-Kent was a pearl of fine quality 

 and considerable size that the exhibitor had caused the mother- 

 of-pearl shell animal, Alehagi-ina vtargaritifera, to produce 

 by means of a delicately-manipulated operation on the living 

 animal. 



From the Zimbabwe ruins, Mashonaland, some very valuable 

 finds in the shape of pottery, gold crucibles, weapons, ingot 

 moulds, &c., were exhibited by Mr. Theodore Bent and the 

 Royal Geographical Society ; while by the same exhibitors were 

 shown a model of the circular temple at Zimbabwe, built of 

 small blocks of granite without mortar ; and several plans of 

 ruins in Mashonaland. No less interesting also were the 

 photographs of ancient Central American monuments and build- 

 ings from the ruins at Chichen Itza (Yucatan), Palenque 

 (Chiapas), &c., exhibitedl by Mr. Alfred P. Maudslay ; and a 

 selection from the proof-plates to the first memoir of the archaeo- 

 logical survey of Egypt that is being undertaken by Mr. Percy 

 E. Newberry. One of these proof-plates showed all the suc- 

 cessive stages of a wrestling match between a black and a white 

 man, more than "a hundred different positions being recorded ; 

 the white man, we are sorry to say, seemed to be getting the 

 worst of it in many of them. 



Several important discoveries were made during the Royal 

 Dublin Society's survey of the fishing grounds on the west coast 

 of Ireland ; specimens of several fish then obtained were exhibited 

 by Prof. A. C. Haddon and Mr. E. W. L. Holt. Many new 

 to British waters were found, while one quite new to science 

 {Nettophichthys retropinuattts, Holt) was caught. 



Some very curious worms composed Mr. F. E, Beddard's 

 exhibit. They were specimens of Bronchi lira Smverbii, and 

 were found in a tank in the Regent's Park Botanical Gardens. 



