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French by Mons, Perrey, by desire of the Government of France ; and 

 into German by M. Jeittels, of the Imperial Gymnasium of Kaschau in 

 Hungary, and of the Imp. Acad, of Sciences, Vienna ; and prior to the 

 breaking out of the war was about being republished, with large addi- 

 tions by the author, by the Smithsonian Institution of America, which 

 offered to circulate at its expense a vast number of copies over the world of 

 science. Prior to the completion of the discussion of the British Association 

 Catalogue, Mr. R. Mallet proposed to the Royal Society and to the British 

 Association, conjointly to undertake further experiments on the pro- 

 pagation of artificial earthquake shocks in stratified rock, by taking ad- 

 vantage of the great blasting operations going on at Holyhead. Aided 

 by the funds of both bodies, he has completed these experiments, ex- 

 tending over a period of about four years, and last year reported to the 

 Royal Society and to the Association. His results will appear in the forth- 

 coming volume of the Philosophical Transactions, and also in the next Bri- 

 tish Assocation Report. They confirm his previous observationss in sand 

 and granite, &c., and comprise also some new and important results ; 

 amongst the rest this, which is new to science — that the rate of propaga- 

 tion of an earthquake shock is faster in the same medium as the originat- 

 ing impulse is more powerful — a fact full of import as respects natural 

 earthquakes, and curiously confirming some of the theoretic views of Mr. 

 Earnshaw. In December, 1 857, occurred the great earthquake of IN'aples. 

 Mr. R. Mallet represented to the Royal Society the importance of observ- 

 ing its effects ; and with the partial aid, and by the desire of that body, he 

 proceeded to the scene of the disaster, and under circumstances of some 

 difficulty and inconvenience, applied new methods devised by him for 

 the investigation of the direction and velocity of the shock. In the ma- 

 thematical part of these inquiries he acknowledges the important aid he 

 has derived from the skill of our fellow-academician. Professor Haugh- 

 ton, Professor of Geology, Trinity College, Dublin. Mr. Mallet's report 

 on this expedition and investigation is now in the press, and will be pub- 

 lished in about six weeks. It was read to the Royal Society in 1860, and 

 an abstract of its contents has been published in the Proceedings of 

 that body. The author fully succeeded in accomplishing what he set 

 out with attempting, namely, to find within the shaken country, by ma- 

 thematical or mechanical appeal to the objects shaken down or disturbed, 

 both the spot on the surface vertically above the point whence the shock 

 itself originated, and also the depth of this point or focus beneath the 

 surface. And he has shown that, in this instance, the focus was about 

 nine and a half geographical miles deep. He has been able to estimate 

 both the shape and the size of the subterranean cavity forming the focus, 

 and to deduce many interesting and valuable conclusions as to the 

 temperature, pressure, work consumed in the shock, &c. The velocity 

 of the wave-particle in shock he has proved to be very small, not more 

 than twelve to eighteen feet per second, thus co-ordinating with the low 

 velocity of transit before ascertained. Amongst other deductions of ge- 

 neral interest, based upon strict mechanical laws, is the probability that 

 the depth of focus of no earthquake exceeds about thirty geographical 



