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CORRESPONDENCE. 
*** The Editor does not hold himself responsible for statements of fads or 
opinions expressed in Correspondence, or in Articles bearing the signature 
of their respective authors. 
A NEW SEISMOGRAPH. 
To the Editor of the Journal of Science . 
Sir, — I notice an article in “ Nature ” for November 3, 1881, 
headed “ Lunar Disturbance of Gravity.” Of course it is pos- 
sible, as I know to my cost, for a new theory to originate with 
the printer’s boy; but the gist of this paper is evidently the 
description of a delicate seismograph, which reflects great credit 
on its constructors. Indeed it is notable there is no effort put 
forth to establish the theory of a disturbance in a — or the if it be - 
land-tide as eliminated from extraneous circumstance during the 
course of the paper, the matter being left among the desirables 
stated at its commencement. One faCt, however, is duly arrived 
at, and circumstantially stated towards the close ; namely, that 
the effeCt of frost and a wet season combined is strongly marked, 
for on January 23rd, 1881, a foundation-stone was 4-12 m.m. 
higher than it was on September 7th, 1880 ; and also that the 
prolonged drought of the present summer (this must refer to 
England, for it has been a proverbially wet year in Scotland) has 
had a great effeCt, for between May 8th and June 29th the stone 
sank through 579 m.m. This matter then, I suppose, is quite 
undeniably Solar Physics proper, and it should tend to place, 
without the bourns of mere theoretical assumption, the notion 
that superficial earth tremours may be so produced. Indeed the 
writer of the paper would lead one on yet farther, for he adds : — 
The changes produced in the height of the stone are, of course, 
entirely due to superficial causes ; but the amounts of the oscil- 
lations are certainly surprising, and although the basements of 
astronomical instruments may be very deep, they cannot entirely 
escape from similar oscillations.” This I suppose to refer to the 
leverage exerted by the expansions and contractions in the crust 
of variable temperature, which, as Page tells us in his “ Text- 
Book of Geology, should be taken to be 60 or 90 feet in vertical 
depth. Indeed, as I understand, it has been already mooted to 
