488 Proceedings of Royal Society of Edinburgh. [sess, 
ence which has lately been going the rounds of the public press, 
under the heading “ On the Trail of a Ghost,” has suggested to no 
less an authority on seismological science than Prof. Milne, that 
the mysterious noises heard might very well he caused by earth 
tremors. If this he so, to trace the connection between cause and 
effect, and “ lay the ghost,” would seem, as he suggests, to be by 
no means difficult. It is surely a pity that the attempt should not 
be made, as the case appears to be one in which physical science 
might well be expected to render some assistance. 
Fig. 1 is reproduced from the bifilar pendulum photographic 
record of the Calcutta earthquake, enlarged to twice the original 
size. 
Figs. 2 to 7 inclusive are reproduced from photographs of various 
dates, reduced to § of the original size, and embrace from 36 to 48 
hours each. The straight line accompanying each of the pendulum 
curves is photographed by a fixed mirror, and serves as a base and 
time line. The disturbances marked 2" are measures of the sensi- 
tiveness of the instrument. 
