96 



which you produced the memoirs for which this medal has been specially 

 awarded, I feel that 1 am justified in referring to them as the results 

 of the same well-trained sagacity which has characterized the whole 

 series of your scientific achievements. 



A Cunningham Medal has been awarded to Mr. Eobert Mallet, for 

 his researches in the theory of earthquakes. Prior to the year 1846, no 

 true science of earthquakes existed; seismology, as a branch of ter- 

 restrial physics, has been since created. Mitchel, Dolomieu, Eylandt, 

 Humboldt, and Darwin, the very latest writers on the subject, prior 

 to 1846, all show that they had no clear conception either of the inti- 

 mate mechanism, or of the connexion and order of events in^ earth- 

 quakes. The only true hints that had been given respecting them 

 were those furnished, in little more than a sentence, by Dr. Young 

 and Gay Lussac, that they were of the nature of vibrations in solids." 

 E"o adequate ideas had been formed of the character and limits of 

 those vibrations, which were vaguely talked of as vorticose. In Fe- 

 bruary, 1846, Mr. R. Mallet's paper on the Dynamics of Earthquakes" 

 was read to the Eoyal Irish Academy, and published in vol. xxi., p. 1, 

 of its Transactions. In this paper he fixed upon an immutable basis 

 the real nature of earthquake phenomena, and for the first time showed 

 that the three great classes of phenomena, — 1. Shocks; 2. Sounds; 

 3. Great sea- waves, — were all reducible to a common origin, formed 

 parts of a connected train, and were explicable on admitted laAvs. 

 This paper also for the first time explained the true nature of the 

 movements that had been called vorticose, and viewed as the proofs, of 

 circular movements. Mr. E. Mallet proved that they were due to recti- 

 linear motions. He also pointed out in this paper the important uses 

 that might be made of earthquakes, as an instrument of discovering the 

 depth beneath the earth's surface of the origin of the shocks,— hence of 

 the volcanic foci, — and even of ascertaining ultimately the nature, as 

 well as the temperature, of the formations within our earth, to a depth 

 more profound than can be reached by any other mode of examination, 

 or reached directly at all. He also showed that by seismologic means we 

 may acquire some knowledge of the rock and other formations consti- 

 tuting the beds of the great oceans. This paper brought the subject 

 of earthquakes in a prominent manner before the notice of geologists and 

 physicists; and in 1849-50, Mr. R. Mallet drew up, at the desire of 

 the British Association, a first report on the facts of earthquake pheno- 

 mena, which, like his subsequent reports, four in all, was published in 

 its Transactions. In this first report, he collected, classified, and drew 

 inductive conclusions from all the important facts then known and pub- 

 lished as to earthquakes, and pointed out how they co-ordinate vdth his 

 first views of 1846. In the same year, he also designed the first com- 

 pletely self-registering Seismometer proposed, and published a descrip- 

 tion of it in our Transa^.tions. In the three papers to which I have 

 referred he pointed out, amongst other things, the importance of experi- 

 mentally determining the velocity of movement of earthquake- waves, and 



