ON THE VOLCANIC PHENOMENA OF VESUVIUS. 34S 



with the snflBciently strong explosions, to project a few lava cakes beyond 

 the crater edges. The bottom of the ci'ater has been invisible owing to 

 the large amount of vapour present on each occasion when I visited 

 the mountain summit. 



Since I quitted Naples an actual crateret has opened in the Atrio at 

 the point where these fumaroles stood, and several gushes of lava have 

 taken place. I shall more fully report on these new phases on my 

 return to Naples. 



Report of the Gotnmittee, consisting of Mr. Gr. J. Symons, Mr. C. 

 Davison {Secretary), Sir F. J. Bramwell, Mr. E. A. Cowper, 

 Professor Gr. H. Darwin, Professor J. A. Ewing, Mr. Isaac Roberts, 

 Mr. Thomas Gtray, Dr. John Evans, Professors J. Prestwich, E. 

 Hull, Gr. A. Lebour, R. Meldola, and J. W. Judd, Mr. M. 

 Walton Brown, and Mr. J. Gtlaisher, appointed to consider 

 the advisability and desirability of establishing in other parts 

 of the country Observations upon the Prevalence of Earth Tre- 

 mors similar to those now being Tnade in Durhayn in connection 

 with coal-mine explosions. 



During the past year the attention of the committee Ihas been directed 

 to ascertaining what instruments have been devised in other countries 

 suitable for the woi'k with which your committee is charged. They 

 believe that that list is now nearly complete, and in their next report 

 they propose to fully describe and illustrate these devices, as they are 

 sure that such a collection of descriptions would be extremely useful. 



This list will certainly contain the following instruments, and probably 

 others of a simpler and less expensive character. 



1. The nadirane erected by M. "Wolf in the observatory of Paris. 



2. The pendulum with do uhle- suspension mirror employed by Messrs. 

 G. H. and H. Darwin at Cambridge in their attempt to determine the 

 lunar disturbance of gravity. 



3. The tromometer used by P. Bertelli at Florence, and by other ob- 

 servers in Italy and Switzerland. 



4. The tremor recorder of Professor J. Milne used by him in Japan . 

 Mr. Horace Darwin has recently invented another form of pendulum, 



smaller and less delicate than the one referred to above. This instru- 

 ment has been made by the Cambridge Scientific Instrument Company, 

 and Mr. Darwin has generously offered to place it temporarily at the 

 disposal of the committee. Experiments will be made with it shortly, 

 an account of which the committee hope to give in. their next report. 



The committee request that they be reappointed, with the addition of 

 Professor C. Gr. Knott and Professor J. H. Poynting. 



