406 STUDIES FOR STUDENTS 
arcual route. The waves, W,, are from the diminished amplitude, 
and the time of their arrival to be ascribed to vibrations transmitted 
in the opposite direction over the antipodes, while the waves W, are 
relatively feeble and the time of their arrival is about 3 hours, 31 
minutes behind that of W,, or that necessary for the waves of section 
5 to make a complete circuit of the globe with a velocity of 3.3 kilo- 
meters per second. The seismogram of the Turkestan earthquake 
of August 2, 1902, indicates these waves W, and W, distinctly.? 
(see Plate IV). 
Milne has recently drawn attention to the interesting fact that even 
in the case of lighter earthquakes, from which the energy is so dis- 
sipated that no record is obtained at the more distant stations, a 
distinct thickening of the lines from the pen of the instrument may 
be noted in the station located at the antipodes.? These “antipodean 
survivors” of the large waves in English home stations may be traced 
to earthquakes in New Zealand, and their survival at the antipodes only 
is to be ascribed to the cumulative effects of waves which converge 
from many great circle routes. 
There is much that is yet only speculation regarding the nature of 
the waves registered by the new seismographs,3 and some of the waves 
which have been indicated in the records of non-astatic pendulums 
have originated in the instruments themselves; but the value of the 
methods devised for locating the disturbed areas seems to have been 
established. This tendency of pendulums to vibrate in their natural 
period is now being corrected by automatic damping devices, with 
which a new epoch in the development of the science is opened. 
In his paper above cited Milne has brought together the results 
already obtained in the location of macroseisms.4 On the basis of 
265 such quakes recorded between 1899 and 1903, twelve seismic 
regions have been located which are either beneath the ocean or 
include both sea and continental border. (See Figs. 1 and 3 of 
t Kikuchi, Joc. cit., p. 68, Fig. 37. 
2 John Milne, ‘Recent Advances in Seismology” (Bakerian lecture), Proceedings 
of the Royal Society, Vol. LX XVII (1906), p. 373. 
3See W. Schliiter, ‘““Schwingungsart und Weg der Erdbebenwellen,”’ Beztrdge 
zur Geophysik, Vol. V (1901), pp. 358, 359- 
4 A later report has been issued with 462 quakes included (Seismological Com- 
mittee of the British Association for the Advancement of Science). See Fig. 2. 
