4 
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ON SEISMOLOGICAL INVESTIGATIONS. 
The epicentre for the first shock has been given at 40° N.L. and 
170° or 180° E.L. (Milne), 30° N. and 170° E. (Oldham), and 50° N, 
and 170° E. (Omori). 
V. On the Apparently Luminous Effects from certain Rocks. 
The object of the following note is to show that at certain times sur- 
faces of chalk or clay slate as they exist in mines and quarries give rise 
to continuous or sudden radiations which make an impression similar to 
that produced ‘sy light upon a photographic film. Various motives led to 
the experiments. Accounts of luminosity in the heavens or on hills at 
the time of large earthquakes are common. One of the last occasions upon 
which phenomena of this nature were observed was at the time of the 
Valparaiso earthquake, August 17, 1906. Mr. W. G. Davis, Director of 
the Meteorological Survey of Argentina, tells me that as seen by Captain 
Taylor from the deck of the R.M.S. ‘Orissa,’ lying fifty metres from the 
wharf at Valparaiso, there appeared upon the hills at a height of about 500 
metres waves of light. These waves, which are compared with chain light- 
ning, extended as far as the eye could reach, and lasted during the first 
shock, of nearly two minutes. 
On these occasions strong earth-currents have affected the working of 
land lines, and needles of galvanometers have been disturbed. In Tokio 
the writer found that an electrometer, whether arranged to record the 
difference of potential between the earth and the atmosphere or between 
the surface of the ground and water-bearing strata at a depth of 30 feet, 
would from time to time suffer large displacements. The times at which 
certain of these were recorded agreed with the times of local earthquakes, 
and might therefore be regarded as the result of a mechanical disturbance. 
When these observations were made teleseismic unfelt movements had not 
yet been recorded, and it was therefore impossible to determine whether 
such disturbances had any true relationship with many unexplained electro- 
meter perturbations. Now we know that unfelt earth-movements may be 
accompanied by movements of magnetic needles and disturbances in the 
records from electrometers. These and kindred observations suggested 
the possibility that a megaseismic collapse might not only produce 
mechanical disturbances through and over the world, but that part of the 
initial energy at the centrum might be converted into another form of 
energy which might be transmitted to all parts of the world simul- 
taneously. When a territory equal in area to the British Islands is 
shattered to such a depth that the homogeneous nucleus of our earth is 
caused to vibrate, as we have indicated, a local transformation of energy 
in the form of light has occasionally been observed. But we have no 
detinite information as to the distance this or its equivalent may be trans- 
mitted. The observation that from time to time a quarry in the Isle of 
Wight, known as Pan Chalk Pit, which I occasionally passed at night, 
appeared to be luminous also, suggested the possibility of hypogenic 
activities, giving evidence of their existence in the form of light. The pit 
or quarry faces north. In winter it is not reached by the sun. Its 
glowings, which apparently rise and fall in intensity, are most noticeable 
after a dull damp day. 
To determine whether these appearances were real, and whether they 
might be connected with other phenomena, I made, with the permis- 
sion of Mr. J. L. Warsap, the following experiments. At the end of a 
