9 
of Bodies moving in Fluids. 
down, fix a scale Q, the weight of which is to be previously 
determined. All the apparatus being thus adjusted, open the 
stop-cock, and let the fluid strike the lever, and put such weight 
into the scale as will just keep the lever in its perpendicular 
situation, and that weight, with the weight of the scale, must 
be just equivalent to the action of the fluid. Thus we get the 
perpendicular effect of the water. Now incline the plane of the 
lever, at any angle, to the direction of the stream, and adjust 
the string perpendicular to the plane, as before ; then put such 
a weight into the scale as will keep the lever perpendicular to 
the horizon, whilst the fluid acts upon it, and you get that part 
of the effect of the fluid which acts perpendicular to the plane. 
In this manner, when the fluid acts oblique to the plane, we 
get the perpendicular part of the force. The second column of 
the following table shows this effect, by experiment, for every 
loth degree of inclination shown in the first column; and the 
third column shows the effect, by theory, from the perpendicular 
force, supposing it to vary as the sine of inclination. 
C&fi (sn tn 'v-h /- 
Angle. 
Experiment. 
Theory. 
oz. 
dwts. 
grs. 
OZ. 
dwts. 
grs. 
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