108 Scientific Proceedings, Royal Dublin Society. 
result was obtained when three or more balls of equal size were 
dropped in. In all cases the balls took up positions equally 
distant round the circumference. 
2. A small weight was attached to the circumference of the 
teetotum. It spun with a wobble. After several trials with balls 
of different sizes, one was found which produced even spinning, 
taking up a position opposite the weight. 
3. The teetotum was half filled with water and covered. It 
spun quite regularly. By carefully arranging the amount of 
water in the teetotum and the weight of a ball which was also 
placed inside it, it was possible to obtain perfectly even spinning. 
All the above results depend upon well-known principles, and 
are introduced to illustrate the matter under consideration. 
By spinning the teetotum on plates of smoked glass, very 
interesting curves may be obtained. 
Without entering into the discussion concerning the exact 
shape of the Earth, or the precise state—whether solid or liquid— 
of its interior, we may consider it as a sphere rotating with 
great velocity, containing, at least at certain localities, masses of 
matter which are capable of undergoing displacement. We are, 
besides, led to believe that volcanic disturbances and earthquakes 
are merely external indications of much greater disturbances 
beneath the surface of the Earth. 
Suppose at a place near the equator there is, owing to whatever 
cause, an upward or downward displacement of matter. This 
would correspond to the addition or subtraction of a weight at a 
point on the circumference of the teetotum. ‘The Harth would 
spin with a wobble. The effect of this would be to produce a 
stress on other points situated on a narrow belt round the Harth’s 
circumference. The places of weakest crust would be the first to 
yield to this stress. If this resulted in a displacement of matter 
at a point diametrically opposite to the original disturbance, it 
would correspond to the addition of a ball to a weighted tee- 
totum. If, however, the first place to yield were some point not 
diametrically opposite, the presence of these two disturbances, 
would, as illustrated by the teetotum experiments, produce a 
displacement at some third point. ‘This would correspond to a 
teetotum containing three balls. A sudden displacement would be 
manifested as an earthquake, while a more gradual displacement 
