W. Dennis on the Theory of the Tides. 237 
than the mean and therefore not quite equal to the centrifugal 
force and here accordingly there will be an excess of this latter 
force: but on this side it is this centrifugal force that acts in a 
direction opposite to that of gravity, and this excess of it will 
consequently disturb the equilibriam of the surface waters here 
_ in precisely the same manner as in the other case. 
eferring now, for illustration, to the suspended ball before 
mentioned, let us suppose it to be a hollow globe one or two feet 
in diameter, of a quite flexible material, as India rubber, having 
an opening about half an inch in diameter at the top and also at 
stiff horizontal wires, which are placed at right angles to each 
other and the extremities of which pass loosely through small 
Openings in the sides of the globe. Passing this cord over a 
eter: and attaching a weight, so adjust the weight that it shall 
sufficient to support the middle horizontal zone or segment of 
the globe. Let there be two other cords with pulleys and at- 
tach one to the top of the globe and the other to the bottom, the 
latter passing down through the opening in the top; then at- 
tach to the former a weight somewhat more than sufficient to sup- 
port the top part of the flexible globe and to the latter a weight 
not quite sufficient to support the bottom part. Now it should’ 
remembered that in this illustration the force of gravity or 
Weight of the globe stands in place of the centrifugal force gen- 
¢ y the earth’s motion in its orbit, and the tension of the 
cords, in place of the sun’s attractive force varying at different 
distances: the cord.attached to the wires at the centre may then 
represent the mean attractive force of the sun at the mean dis- 
or most remote side. The globe being flexible, it is evident that 
the top part will be drawn up somewhat by the excess of the 
