732 Meeting of the British Association. [Oct., 



insulated with gutta-percha. The subject, therefore, had an important 

 bearing in a financial point of view, as well as in other respects. 



This paper was followed by a discussion upon the causes of failure 

 of the Atlantic Telegraph, on which remarks were made by Messrs. 

 Siemens, Fairbairn, Fleeming Jenkin, Cyrus Field, Capt. Selwyn, and 

 O. Byrne. 



Mr. H. C. Sorby then briefly described his new form of Spectrum 

 Microscope. He mentioned its powers and uses in several instances, 

 andjamongst others, said that in identifying blood marks, they could 

 employ it to detect the most minute stains : even of the one-millionth 

 part of a grain they could have a perfect spectrum. 



The proceedings concluded by a brief description by M. Claudet of 

 his " Moving Photographic Pictures," detailing the means by which 

 this effect was produced, j 



The proceedings of Friday, the 8th September, opened with the 

 report of the " Lunar Committee," read by Mr. Glaisher, the chairman, 

 which treated of the steps taken by the Committee during the past 

 year to prepare a large and accurate map of the moon's surface. 



At the conclusion of this report Mr. Birt (Secretary to Lunar 

 Committee) read a paper " On the Progress of the Map of the Moon." 

 Mr. Birt described by a diagram, how the moon's surface was divided 

 and subdivided into sections, the larger parts being designated by a 

 letter of the Roman alphabet, and the smaller divisions by the smaller 

 letters of the Greek alphabet. By this means they could record any 

 observations they had made, in such a way that observers coming after 

 would be able to discover the locality. Having described the tele- 

 scopes used in making observations, Mr. Birt went on to speak of 

 various conspicuous objects on the moon's surface, such as the crater 

 " Plato," the " Teneriffe mountains," the " Dionysius Crater," the 

 " Railroad," the " Terra Photographica " of Mr. Warren De la Rue, 

 &c, pointing them out in a diagram as he proceeded with his remarks. 



The next communication was by Mr. Balfour Stewart and 

 Mr. J. P. Capello, " On the Magnetic Storm of the Beginning of 

 August last, as recorded by the Instruments at Kew and Lisbon." 



Having described the means of ascertaining the value of the force 

 which disturbed the needle, Mr. Stewart said the storm he was about 

 to describe was the very great magnetic storm which many would 

 remember from its having occurred at the time anxiety began to be 

 felt about the Atlantic cable. It had many curious points, and 

 was very similar to a great magnetic storm which occurred in 

 August, 1859, being accompanied by great auroral phenomena and 

 disturbance of the telegraph wires. There were instruments in the 

 Observatories at Kew and at Lisbon, by the aid of which any dis- 

 turbance was continually recorded by the aid of photography. The 

 characteristics of a magnetic storm were not local in their nature, but 

 cosmical, affecting different places at the same time. The way in 

 which the storm of August affected the magnet was almost the same 

 at Lisbon and Kew. It broke out on August the 1st, and lulled and 



