[ T 33 ] 
If a ftream of water falls into the bucket of an 
overfhot wheel, it is there retained till the wheel 
by moving round difcharges it : of confequence the 
flower the wheel moves, the more water each bucket 
will receive : fo that what is loft in fpeed, is gained 
by the preflure of a greater quantity of water adting 
in the buckets at once : and, if conftdered only in this 
light, the mechanical power of an overfhot wheel to 
produce effects will be equal, whether it moves quick 
or flow : but if we attend to what has been juft now 
obferved of the falling body, it will appear that 
fo much of the adtion of gravity, as is employed in 
giving the wheel and water therein a greater velocity, 
muft be fubtradted from its preflure upon the buckets ; 
fo that, tho’ the produdt made by multiplying the 
number of cubic inches of water adding in the wheel 
at once by its velocity will be the fame in all cafes ; 
yet, as each cubic inch, when the velocity is greater 
does not prefs fo much upon the bucket as when it 
is lejf the power of the water to produce effedts will 
be greater in the lefts velocity than in the greater : 
and hence we are led to this general rule, that, 
ceteris paribus, the left the velocity of the wheel the 
greater will be the eff’eSl thereof. A confirmation of 
this dodtrine, together with the limits it is fubjedt to 
in pradtice, may be deduced from the foregoing fpe- 
cimen of a fett of experiments. 
From thefe experiments it appears, that when the 
wheel made about 20 turns in a minute, the effedt 
was, near upon, the greateft. When it made 30 turns, 
the efifedt was diminifhed about - 1 - part but that 
when it made 40, it was dimimiftied about ft when 
it made lefs than 18 ft, its motion was irregular and 
when 
