740 



SCIENCE. 



[N. S, Vol. VII. No. 178. 



son, showing the production of cloud by the 

 action of ultra-violet light, suggesting an 

 explanation of the blue in the sky. Pro- 

 fessor Hele-Shaw's delicate experiments on 

 the flow of water deserve mention. They 

 are of practical moment also, as are Mr. T. 

 Andrew's micrographic illustrations of de- 

 terioration in steel rails, indicating the 

 microscopic structure and composition of 

 the most enduring and safest rails. Pro- 

 fessor Roberts- Austen showed a complete 

 installation of apparatus for the micro- 

 photography of metals designed for Sir 

 Andrew Noble for use at Elswick Works, 

 also apparatus to illustrate M. Daniel 

 Berthelot's interference method of mea- 

 suring high temperatures. It consists of 

 an optical interference apparatus in 

 which a beam of light is divided by a 

 thinly-silvered mirror and passed through 

 two tubes. In one of these tubes air is 

 rarefied by heat and in the other by ex- 

 haustion, and when the rarefaction is equal 

 in both tubes colored interference bands 

 appear. As the degree of exhaustion in one 

 tube can be measured by a manometer the 

 unknown temperature is readily found. 

 Mr. Horace Seymour, Deputy-Master of the 

 Mint, exhibited a case of bronze Jubilee 

 medals beautifully colored by a method, 

 borrowed from the Japanese, which marks 

 a new departure in medal work in this 

 country. Mr. J. E. Stead sent some re- 

 markable specimens of iron and steel, show- 

 ing crystalline structure developed at 

 750°C., the temperature at which the mag- 

 netic change in iron takes place. They 

 proved that their peculiar polj'gonal struc- 

 ture could be produced without the presence 

 of a cementing material between the joints, 

 and showed clearlj' the existence of allo- 

 tropic forms of iron. Professor Ewing ex- 

 hibited a magnetic balance for permeability 

 tests of iron. It is a new apparatus de- 

 signed to afford an easy means of judging 

 of the magnetic quality of iron or steel. 



with special reference to its suitability for 

 use in dynamo magnets. 



An attractive exhibit was that of Mr. 

 Joseph Goold's experiments in relation to 

 resonance, which were harmonics, sub-har- 

 monics, and compound harmonics illustrated 

 by the action of forced vibrations in paper 

 discs, thin metal plates, etc. ; also vibration- 

 tops, which spin by contact with vibrating 

 surfaces, and vibrating dust-heaps bursting 

 into whirling nebulse and condensing into 

 gravitating systems of circular mounds. 



Those who attended the meeting of the 

 British Association last year were inter- 

 ested in Professor Poulton's Canadian in- 

 sects and Dr. Armstrong's colored photo- 

 graphs of the Yellowstone Park. The 

 series of models illustrating the composi- 

 tion of vertebrse in the various groups of 

 vertebrata, exhibited by Dr. Gadow and 

 Mr. W. F. Blandford, were highly instruc- 

 tive. The ' naturographs ' shown by Mr. 

 R. B. Roxby were beautiful specimens of 

 Dr. Selle's process of photography in natural 

 colors. 



Every one was naturally interested in 

 the exhibit by Professor Herdman and Pro- 

 fessor Boyce of healthy and unhealthy 

 oysters, showing the causes of coloration 

 and the connection between oysters and 

 disease. The exhibit by the Marine Bio- 

 logical Association of the adaptation of 

 marine animals to their environment, illus- 

 trated by living examples of the higher 

 Crustacea, was highlj^ instructive and in- 

 terested many. There were several other 

 interesting biological exhibits and demon- 

 strations. It is impossible even to mention 

 many other exhibits, some of them of at 

 least equal scientific importance to those 

 referred to. 



During the evening, besides Sir Norman 

 Lockj'er's eclipse exhibit, shown by means 

 of the electric lantern, Dr. Sorby showed 

 some cleverly mounted slides illustrating 

 marine animals. 



