282 SIR RODERICK I. MURCHISON'S ADDRESS. [May 23, 1859. 



Association, and by means of a new instrument (the seismoscope) and 

 the creation of small but real earthquakes at pleasure by mines of gun- 

 powder filed galvanically at the distance of a mile, he was enabled 

 to ascertain the actual relative rate of transit of the earth wave or 

 shock in loose sand, in shattered as well as in solid unbroken 

 granite ; * it being thus determined that an earthquake cannot 

 move slower than in sand, nor probably faster in any known rock 

 than in granite. These experiments Mr. Mallet, with the joint aid 

 of the British Association and of the Eoyal Society, has since ex- 

 tended to some stratified rocks. Mr. Mallet has also condensed his 

 views into the form of instructions for earthquake observation in 

 the Admiralty Manual, and the Article has been translated into 

 French by Mons. Perrey, at the desire of his Government. 



The laborious compilation of the vast catalogue, comprising be- 

 tween six and seven thousand earthquake narratives, thus early 

 projected, had been steadily pursued by Mr. Mallet, ably assisted 

 by his eldest son, Dr. John William Mallet, of the University of 

 Alabama, U.S., from 1852 to 1858, and last year the 'British Asso- 

 ciation Earthquake Catalogue,' by these authors, appeared in print, 

 with the most complete discussion by curves and seismic maps ever 

 made, and giving, so far as human knowledge goes, the facts of 

 seismic distribution in time and in space. f Several deductions of 

 interest and importance have resulted from this extensive labour, 

 the most important of which is probably the now ascertained fact, 

 that mere farther cataloguing is useless as regards the advance of 

 science ; since Mr. Mallet considers that no great generalization can be 

 thus elicited. Looking to the true direction in which the efforts of 

 seismologists are to operate, he recommends observation at self- 

 registering seismometrical establishments at suitable localities in 

 certain earthquake regions. The latter portion of his final Report 

 is devoted to the description of the various forms of seismo- 

 meters proposed by divers authors, and he has figured the pre- 

 ferable forms of seismometric apparatus to be adopted, which have 

 resulted from the labours and experimental investigations of several 

 years. The electro-seismic trigon, as his arrangement may be 

 called, as well as the various simpler and ruder methods of approxi- 

 mate observation pointed out to the traveller in the Admiralty 



* Second Report, Trans, Brit. Assoc. 1851. 



t Mr. Mallet and his son acknowledge the important lightening of their labours by the 

 previous large and valuable catalogues of Von HofF, and especially of Professor Perrey of 

 Dijon, to whose collaboration in the seismic field they give the highest praise. {See Mem. 

 Acad. Roy. deBelgique, torn, vii., in oct.) 



