242 Dr. C. Davison—Fownders of Seismology— 
Rhine. Of the other continents, only special regions are considered—. 
in Asia, the Philippine Islands, Japan, and the Kurile Islands and 
Kamschatka ; in Africa, Algeria and the north of the continent ; 
in America, the Antilles, Chile, Peru, and the Aleutian Islands, 
Alaska, etc. Regarding the interior of the earth as fluid, it was 
only natural that Perrey should investigate a lunar periodicity! in 
the occurrence of earthquakes, but his three laws of greater frequency 
at syzygies than at quadratures, at perigee than at apogee, and, for 
any place, when the moon crosses the meridian, can hardly be 
regarded as possessing a firm foundation. His chief claim to our 
gratitude rests on his extensive catalogues. Our knowledge of the 
history of nearly every seismic region of the globe depends at one 
point or another on the untiring labours of Alexis Perrey. 
In other respects the ground was unoccupied. Our knowledge 
of individual earthquakes was gradually increasing, the facts of 
earthquake phenomena were becoming known, but, as yet, there 
was no science of seismology. The next step was made, not by a 
trained student, but by a busy practical engineer; and when we 
think of the work which Mallet accomplished for seismology we should 
also remember that it was done, for the most part alone and unaided, 
in the midst of great engineering enterprises. 
Robert Mallet was born at Dublin on June 3, 1810, his father, 
John Mallet, being the proprietor of a factory in which sanitary 
fittings and small fire-engines were made. At the age of 16 
Mallet entered Trinity College, Dublin, taking the degree of B.A. 
after a four years’ course. In the following year (1831) he married 
and was taken into partnership in his father’s factory. This he soon 
converted into engineering works with a considerable foundry, and 
before many years had passed all the engineering work of any 
consequence in Ireland was carried out by the firm. Mallet’s first 
great feat was to raise the roof of St. George’s Church, Dublin, a 
mass 133 tons in weight, and covering a large area. This was 
_ followed by the building of several bridges over the Shannon, and the 
invention and construction of hydraulic rams and of ventilating and 
heating apparatus for public buildings. His buckled plates, which he 
began to make in 1840, form one of the best floors ever designed, 
combining the maximum of strength with the minimum of depth and 
weight. They are to be found on the Westminster and other London 
bridges. In 1845-6 he was erecting a-railway station while he was 
working at his first important paper on the dynamics of earth- 
quakes. In 1849-55 he built various station roofs, and the Fastnet 
Rock lighthouse, and was designing heavy guns and large mortars, 
the latter capable of throwing 36 inch shells. At the same time he 
1 It is interesting to notice that the possibility of a lunar periodicity occurred 
to Darwin in 1840. Writing to D. Milne, he remarks, ‘‘ On the hypothesis of 
the crust of the earth resting on fluid matter, would the influence of the moon 
(as indexed by the tides) affect the periods of the shocks, when the force which 
causes them is just balanced by the resistance of the solid crust?’’ (More 
Letters of Charles Darwin, vol. ii, 1903, p. 115). 
