248 Notices of Books. [April, 



outlines and relations of the two branches of scientific investi- 

 gation — vulcanology and seismology — by which its true nature 

 and part in the cosmos are chiefly to be ascertained." He re- 

 marks, by way of defining his subject, that " Vulcanicity properly 

 comprehends all that we see or know of actions taking place 

 upon and modifying the surface of our globe, which are referable 

 not to forces of origin above the surface, and acting superficially, 

 but to causes that have been or are in operation beneath it. It 

 embraces all that Humboldt has somewhat vaguely called " the 

 reactions of the interior of a planet upon its exterior." He in- 

 dicates the relation between astronomy and physical geology, 

 which overlap each other, through vulcanicity. He then sketches 

 the history and progress of knowledge in the chief domains of 

 vulcanicity. In discussing the more recent contributions to the 

 science, commencing with his early paper " On the Dynamics of 

 Earthquakes," which appeared early in 1846, he takes occasion to 

 point out that Mr. Hopkins, of Cambridge, in his Report " On 

 the Geological Theories of Elevation and Earthquakes," read 

 before the British Association in June, 1847, did him some in- 

 justice. He remarks, that if his paper be compared with Mr. 

 Hopkins's Report, it will be found that as respects the earthquake 

 part, the latter work parades in a mathematical dress some 

 portion of the general theory of earthquake movements, pre- 

 viously published by Mr. Mallet. " This," he proceeds, " is but 

 too mystifyingly suggestive of the ' Pereant qui mea ante mihi 

 dixerunt ' " (a somewhat novel rendering of the hackneyed 

 quotation, by the way). We dwell on this point, because in 

 Prof. Phillips's " Vesuvius," the injustice (unintentionally, of 

 course) is continued, and the theory of earthquakes is too im- 

 portant a contribution to science to be handed over to one who 

 certainly was not its author. The definition of an earthquake 

 in Mr. Mallet's paper of 1846 sufficiently indicates the main 

 teaching of his theory; an earthquake he there says, is " The 

 transit of a wave or waves of elastic compression in any direction, 

 from vertically upwards or horizontally, in any azimuth, through 

 the crust and surface of the earth, from any centre of impulse or 

 from more than one, and which may be attended with sound and 

 tidal waves dependent upon the impulse and upon circumstances 

 of position as to sea and land." The whole paper should, how- 

 ever, be carefully studied by those who wish to form a just 

 opinion of the position in which Mr. Mallet stands with respect 

 to the view of earthquakes, soon to become the established theory 

 on the subject. 



From the date of the publication of that paper until that of 

 the paper recently contributed by him to the Royal Society, Mr. 

 Mallet has continued his researches, experimental and mathe- 

 matical, and the views to which he has been led may be regarded 

 as affording, in the main, the most complete and satisfactory 

 account of the phenomena of earthquakes and volcanoes yet 



