Machine for carrying Vessels out of and into Harbours, fyc. 275 
If it should be said, that I have filled this tract with things that 
are foreign to the matter proposed, I answer, there is nothing in it 
but what is necessary to be understood by those that desire to 
know' the nature of that machine which I now offer to the world : 
and I hope, that, through the blessing of God, it may prove 
serviceable to my country. 
44 In some convenient part of the tow-boat, there is placed a 
vessel about two-thirds full of water, with the top close shut. 
This vessel being kept boiling, rarifies the water into a steam. 
This steam being conveyed through a large pipe into a cylindrical 
vessel, and there condensed, makes a vacuum, which causes the 
weight of the atmosphere to press on this vessel, and so presses 
down a piston that is fitted into the cylindrical vessel, in the 
same manner as in Mr Newcomeris engine, with which he raises 
the water by fire. 
In Plate VIII. Fig. 1., P is the pipe coming from the furnace 
to the cylinder. Q The cylinder wherein the steam is condensed. 
R The valve that stops the steam from coming into the cylinder, 
whilst the steam within the same is condensed. S The pipe to 
convey the condensing water into the cylinder. T A cock to 
let in the condensing water when the cylinder is full of steam and 
the valve p is shut. U A rope fixed to the piston that slides up 
and down the cylinder. Note. — This rope U, is the same rope 
that goes round the wheel D in the machine. Fig. 2. 
46 It hath been already demonstrated, that a vessel of 30 inches 
diameter, which is but two foot and a-half, when the air is driven 
out, the atmosphere will press on it to the weight of 4 ton 
16 hundred and upwards. When proper instruments for this 
work are applied to it, it must drive a vessel with a great force. 
44 Note. — The bigness of the machines may be proportioned to 
the work that is to be performed by them ; but if such a force 
as is applied in this first essay, be not sufficient for any purpose 
that may be required, there is room to make such addition as 
will move an immense weight with tolerable swiftness, 
44 It is my opinion, it will not be found practicable to place the 
machine here recommended, in the vessel itself that is to be taken 
in or out of the port, &c. but rather in a separate vessel, for 
these reasons : 1. This machine may be thought cumbersome, 
s 2 
