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ment, that the rumbling of the carts along the street caused 
more commotion amongst the crockery than the generality of 
the tremors. : 
T have dwelt at considerable length upon this branch of 
the subject, namely, the extreme actual minuteness of the 
earth-movement, besause [ have to combat an almost 
universal impression that is directly opposed to my deduc- 
tions. The question will naturally arise—How are we to 
account for this impression? I am inclined to think these 
tremors are vibrational—our nerve-system is peculiarly 
sensitive to vibrations. The vibration of a great organ pipe 
may be feltas well as heard. A tap with a walking stick 
upon the end of a 20ft. log will be distinctly felt by a person 
sitting on the other end. I have, while reclining on a spring 
sofa, felt the vibration from a passing cart during its passage 
along the whole length of the block. 
Mr. Jackson, machinist, of Patterson-street, Launceston, 
informs me that he spent some years in Japan, having left only 
recently, where he was employed mechanically in the con- 
struction of Mr. Milne’s successful seismometers. He assures 
me that our tremors are very insignificant in comparison with 
those prevalent in Japan, our strongest shocks only being 
comparable to their weak ones. 
With regard to the position of the focus, I assumed that there 
were two modes of arriving at a solution of the question, the 
one being a careful analysis of the lines of direction, and the 
other a comparison of the times at which the shock was felt in 
different localities. The first method, however, was found 
to fail in practice, probably owing chiefly to the fact that 
the molecular motion of a body in vibration is distinct and 
different from the actual wave progression. The second 
mode was rendered difficult and uncertain by the fact that 
the time quotations were evidently in many cases inaccurate 
and inconsistent. 
Undoubtedly the tremor of 18th July, last year was, as I 
have said, by far the greatest of the series, and, from she 
wide range over which it was felt, was the first to furnish 
sufficient data from which to form anything like an approxi- 
mate estimate of the position of its focus. I made a very 
careful analysis of the time records of this wave, which was 
published in the Launceston Examiner of 22nd July. The 
principle which I applied to this investigation I more parti- 
cularly specified in a subsequent communication to the same 
paper, dated September 2, 1884, as follows:—I assumed 
that the earth-wave,‘ should progress in amore or less irregular 
expanding circle, having the focus of disturbance in the 
centre ; consequently there should be points situated all round 
