March 29, 1888] 



NA TURE 



521 



Mercury at greatest distance fiom the Sun. 

 Venus at greatest distance from the Sun. 

 Uranus in opposition to the Sun. 

 Saturn, April l. — Outer major axis of outer ring = 42" '8 ; 

 outer minor axis of outer ring = 1 5" "5 : southern surface visible. 



THE ROYAL METEOROLOGICAL SOCIETY S 

 EXHIBITION. 



■pOR several years past the Royal Meteorological Society has 

 " organized an Exhibition of Meteorological Instruments in 

 connection with its ordinary meeting in March. The first Ex- 

 hibition, which was held in 1880, wa.s of a general character; 

 the subsequent ones, however, have been devoted to the follow- 

 ing special subjects, viz. hygrometers, anemometers, travellers' 

 instruments, thermometers, sunshine recorders and radiation in- 

 struments, barometers, and marine meteorological instruments. 



The subject selected for this year's Exhibition was atmospheric 

 electricity, including new meteorological instruments. The 

 Exhibition was held in the rooms of the Institution of Civil En- 

 gineers, 25 Great George Street, Westminster, from March 20 

 to 23, and was of a most interesting character. The catalogue 

 embraced 155 exhibits, which were arranged under the following 

 heads : — Electrometers, lightning conductors, lightning pro- 

 tectors for telegraph purposes, objects damaged by lightning, &c. ; 

 alleged thunderbolts, new instruments, photographs of flashes 

 of lightning, and photographs, drawings, &c. 



The Astronomer-Royal exhibited all the apparatus for atmo- 

 spheric electricity which was formerly in use at the Royal 

 Observatory, Greenwich. These instruments were mounted so 

 as to show the manner in which they were actually arranged fur 

 observation. 



The Kew Committee also exhibited a number of electro- 

 meters which were employed by Sir Francis Ronalds at the Kew 

 Observatory from 1843 to 1851. These are fully described in 

 the Report of the British Association for 1844. Several forms 

 of Thomson's portable electrometer were also shown. The 

 electricity in this instrument is collected by means of a burning 

 fuse at the extremity of a vertical wire. Prof. F. Exner, of 

 Vienna, sent his portable apparatus for the determination of the 

 normal potential in the open air and while travelling. 



Numerous patterns of lightning conductors were exhibited by 

 Messrs. J. W. Gray and Son, Messrs. R. Anderson and Co., 

 Messrs. John Davis and Son, and also by the Lightning Rod Con- 

 ference. Models of churches, houses, chimney-shafts, &c. 

 showed the systems adopted for securing protection from 

 damage by lightning. Messrs. Siemens, Brothers, and Co., also 

 exhibited their apparatus for testing the efficiency of lightning 

 conductors. 



The Postal Telegraph Department showed a number of 



lightning protectors which are used for protecting telegraph 

 instruments. 



The Exhibition contained many objects damaged by lightning, 

 including lightning conductors, telegraph instruments and line 

 wire, and portions of trees struck by lightning. The most in- 

 teresting exhibit, however, was that showing the clothes of a 

 man torn off his body by lightning on June 8, 1878, while stand- 

 ing under a tree. These comprise a flannel jac'Ket, flannel under- 

 vest, trouser.'^, stockings, garters, boots, and watch ; also a portion 

 of the bark from the tree. 



A valuable collection of meteorites was also shown, the 

 specimens being from various parts of the world, and one show- 

 ing the Widmanstatten figures. A number of alleged "thunder- 

 bolts " were also exhibited. These were of an amusing character ; 

 the specimens being in reality nothing more than a large nodule 

 of sandstone, a cannon-ball, a piece of coal, clinkers, &c. Mr. 

 Symons, at the meeting of the Society, showed that these were 

 really of a terrestrial, and not a celestial, nature. 



One of the special features of the Exhibition was the very in- 

 teresting collection of more than fifty photographs of flashes of 

 lightning which have been collected from all parts of the world. 

 These show that lightning does not take the zigzag path as de- 

 picted by artists and painters. The lightning really takes a very 

 sinuous and sometimes erratic path. Some of the photographs 

 had been enlarged specially for the Exhibition, and showed up 

 10 great advantage. In some cases the photographs showed the 

 lightning to be not merely a line of light, but to have a per- 

 ceptible breadth, somewhat resembling a piece of tape waved in 

 the air. A large number of the photographs were taken in 

 London during the great thunderstorm of August 17, 1887. One 

 of the photographs taken by Mr. E. S. Shepherd shows the 

 remarkable phenomenon of a dark flash. 



Mr. Symons exhibited three diagrams of lightning made by 

 Mr. James Nasmyth, F. R. S., in 1856, showing (i) Nature's 

 lightning ; (2) painter's lightning ; and (3) forked lightning. On 

 com.paring these drawings with the photographs of lightning, it 

 is at once apparent what a keen eye Mr. Nasmyth must have 

 had, for the agreement is exceedingly close. 



Several new meteorological instruments were exhibited. Mr. W. 

 H. Dines showed a maximum wind pressure anemometer. This 

 has a circular plate, which is always kept face to the wind, at 

 the back of which is a vessel containing shot. The pressure of 

 the wind forces back the plate, and allows shot to fall from the 

 higher to the lower part of the vessel. As soon as the weight of 

 the shot in the lower vessel is equal to the whole pressure on the 

 plate, the plate resumes its normal position, and the opening 

 through which the shot falls is closed. The weight of the shot 

 in the lower vessel gives the maximum pressure since the instru- 

 ment was last read. Mr. G. H. Larkins showed some rain- 

 band spectroscopes with Tripe's arrangement. The improve- 

 ments in this instrument over the ordinary form of direct-vision 

 spectroscope are : (1) that it gives uniform light and dispersion, 

 and also better definition of the lines ; (2) that as the slit is of 

 uniform width, observations made with this form of instrument 

 are comparable with each other ; and (3) that the focussing tube 

 can be fixed by a revolving clamp and kept ready for use. 



Dr. Marcet exhibited Prof. Colladon's instrument for illus- 

 trating the formation of waterspouts. This consists of a large 

 glass vessel, at the bottom of which has been scattered some 

 dust somewhat heavier than the water. The motion given to a 

 handle turns a wheel which imparts to the water a circular 

 motion. The dust is then drawn up from the bottom in a 

 column, and looks exactly like a waterspout or a sand pillar. 



Mr. J. B. Jordan showed one of his new pattern photographic 

 sunshine recorders (in which he now obtains a straight record 

 instead of a curved one), and also that devised by Dr. J. Maurer, 

 of the Swiss Central Observatory, Zurich. 



Mr. G. M. Whipple exhibited his repeating cloud camera, 

 which has been designed for obtaining a series of four photo- 

 graphs of the same cloud at short intervals of time, in order to 

 show rapid changes of form. 



Numerous photographs of damage by lightning were shown, 

 as well as several records of atmospheric electricity taken at the 

 Greenwich and Kew Observatories during thunderstorms and 

 snowstorms. Messrs. Norman May and Co., exhibited two 

 beautiful photographs taken from the top of the Worcestershire 

 Beacon (1390 feet above sea-level), about 700 feet above the 

 general level of the fog which covered the whole of the surround- 

 ing country, on January 12 last. Above the fog there was bright 

 sunshine. 



