MESSES. J. MILNE AND T. GEAY ON SEISMIC EXPEEIMENTS. 
871 
The only exceptions, which were two in number, where the above description of the 
motion does not apply, was when the ball only fell a short distance (8 and 11 feet), 
and the observing point was at the 50 feet station. In these two instances simply a 
series of long narrow ellipses were drawn, their longer axes being in the direction of 
the line joining the position of the falling weight and the instrument. 
Of the other figures which were drawn we give three examples, each of which show 
the motion of the ground magnified 85 times. It will be seen that these figures are 
so arranged that their greatest lengths are parallel. The direction of greatest motion 
was that of a line joining the instrument and the point where the ball fell. 
At the commencement the needle of the pointer was resting at or very near to the 
centre of the figure C. In all cases when a clear diagram was obtained it moved to A, 
then down to B, and back again towards C. At or about this point its motion was 
suddenly deflected. In many cases this deflection took place nearly at right angles to 
the first motion, as is shown in fig. 1. Here a great number of flattened ellipse-like 
figures were drawn one on the top of another so as to render this central portion of 
the diagram confused. 
MPCCCLX XXII, 5 T 
