876 MESSRS. .T. MILNE AND T. GRAY ON SEISMIC EXPERIMENTS. 
Transverse vibrations. 
Fall 32. 250 feet station. 
The transverse motion commenced slowly. After 1*5 second it rose to an 
amplitude of 3 millims., and it continued, hut gradually fa lling , for more than 
6 seconds. 
Normal vibrations. 
Fall 33. 250 feet station. 
There appears to have been about 6*5 normal vibrations per second. 
The first distinct motion is apparently one of suction or drawing in of the 
ground towards the point where the blow was struck. The maximum motion is 
very near to the commencement of the record, which can only be seen for a 
length equivalent to a period of 3 seconds. 
Normal vibrations. 
Fall 34. 250 feet station. 
About 11 normal vibrations are visible. There appears to have been 5’5 vibra¬ 
tions per second. The amplitude at the commencement is 1 millim. At the end 
of 1 second it is ’5 millim. This amplitude decreases regularly to zero, which is 
reached at the end of 4 seconds. 
At first there is a very slight motion of compression. The first distinct motion 
is one of suction or drawing inwards towards the weight. The motion reaches a 
maximum *25 second from the commencement. 
Transverse vibrations. 
Fall 35. 250 feet station. 
Here there are 6 waves per second. The movement commenced faintly, rose to a 
maximum of 1 millim. after about 1 second, and then died out as it commenced. 
Motion was observed for 4 seconds. 
Normal vibrations. 
Fall 36. 100 feet station. 
The first distinct motion is a rarefaction or drawing in towards the weight. 
The greatest amplitude is 2'25 millims. Simultaneously with this record, a 
complete record of the vertical motion was drawn. (See seventh set of 
experiments.) 
Seventh Set of Experiments. 
These experiments were made for the purpose of determining vertical motion. The 
instrument employed was a cylindrical tin can half-filled with water, with a flexible 
sheet indiarubber bottom. As this can is raised or lowered, the flexible bottom 
