III. John Milne. 387 
shock, the Jatter alone being found to possess any value. These 
enabled him to fix the position and form of the epicentral area. 
To determine the depth of the focus he measured seven angles ‘of 
emergence at Tokyo and Yokohama from the horizontal and vertical 
motions given by various instruments, and concluded that the most 
probable of the resulting depths are from 14 to 5 miles. Two 
other subjects on which Milne collected many observations were 
also considered—the rotation of chimneys and gravestones and the 
nature of the damage to buildings. In the Yokohama cemetery, for 
instance, the gravestones are arranged in parallel rows, and the stones 
were rotated in one direction only. This uniformity of rotation is 
clearly inconsistent with the explanation given by Mallet, and 
Milne preferred one suggested to him by his colleague T. Gray. 
The other subject, then and afterwards, was constantly before Milne’s 
mind, and in this paper we see his first attempt to provide rules for 
the construction of earthquake-proof buildings. 
Under this heading may also be included the paper on the Peruvian 
earthquake of 9th May, 1877, though it refers mostly to the sea-waves 
which were propagated across the Pacific to the coasts of Japan. 
The position of the epicentre was ascertained from observations 
on the time of occurrence, and one of the chief conclusions of the 
paper is that the mean depths, calculated from the measured 
velocities by means of the formula v = v (gh), are less than those 
obtained from soundings. Milne suggests that the figures obtained 
from soundings may be excessive, but it was afterwards shown 
that the inequality observed must result from variations in the 
depth of the ocean.* 
Construction of Ser i 
thirty or forty years it would seem that the chief debt that we owe to 
the Seismological Society of Japan is the construction of accurately 
recording seismographs. In the designing of these instruments 
the larger share fell to J. A. Ewing and T. Gray, the former being 
responsible for the invention of the horizontal motion seismograph 
(1880) and the duplex pendulum seismograph (1882), and the latter 
for that of the vertical motion seismograph (1881). To Milne we 
are indebted for the testing of the various instruments and for many 
improvements in detail. “Probably no other seismologist has had 
so wide an experience as Milne of the seismograph in all its different 
forms. He wisely began with the simple apparatus in use at Comrie 
forty years before, and with those recommended, but not tested, 
by Mallet in the “ Admiralty Manual”; but common pendulums, 
vessels filled with liquids, bodies floating in water, columns cylindrical 
and otherwise, and vertical springs were all, for one reason or another, 
found wanting. For several years (1872-85), the Tokyo earth- 
quake record was made by a Palmieri seismograph. In the latter 
year this instrument was replaced by a Gray-Milne seismograph, 
' Trans., vol. 1, pt. 2, 1880, pp. 1-116; vol. 2, 1880, pp. 50-96; see also 
Phil. May., vol. 43, 1897, pp. 33-6. 
