( 4'4 ) 
In the Figure afore- mentioned, this Machine has 
but two Branches j however, it may be form’d of 
three, if not four, and adjulted to the fame Standard 
or Meafure : But as three or four Branches would be 
more fubjed to entangle themfelves in Sea- Weeds, 
and thereby prevent the regular Motion of the Inflru- 
ment, if not in fome Meafure impede the Ship’s Way, 
I cannot but recommend their being made only of two 
Branches, in the Manner 1 have laid down ; for, in 
my own Experiment at Sea, I have obferv’d thofe 
made in this Form have been fo far from being 
choak’d by Weeds, that if they encountered any at 
any Time, they have always cleared themfelves of 
them, without the Trouble of hauling the Engine in- 
to the Ship to do it. 
To regulate this Inftrument, it may be done feve- 
ral Ways:, as hrft, by opening or doling the Angle 
CEDj fecondly, by lengthening or fhortening the 
Branches, or turning or bending more or lefs the 
Pallets AKCL and BHDI^ and fo in this Manner 
the Machine is brought to what Standard or Meafure 
you pleafe, to make the hydraulical Revolution to an- 
fwer either to a geometrical Pace of 5 Feet, or to. 10, 
12, 14 Feet, &c . 
The Machines of this Kind, which I have tried at 
Sea in ail Sorts of Weather, did weigh fome 4, others 
5, and others 6 Pounds } the Weight of them not 
at all afFeciing the peculiar Property of the Inflru- 
ment, or hindering the Regulation thereof according 
to the Methods 1 have laid down. 
Thefe Machines may be made of Tin as well as 
Iron, and fo light as not to weigh above two or three 
Pounds, which may ferve for any Boat, Wherry, Barge, 
&c. without any Hindrance to their Rowing or Sail- 
ing. The Manner of fixing them to a Ship, or Boat, 
is reprefen ted in Fig. 6 . I 
