424 Description of an efficacious Temporary Rudder: 
Reference to the Engraving of Captain Prat’s Temporary’ 
Rudder, which can be quickly fitted out by a Ship’s Com- 
pany when at Sea, and from such Materials as they always 
have on board. See Plate VI. fig¢ 1, 2, and 3, ; 
Plate VI. fig. 3. shows all the part of this contrivance de- 
tached, and ready for launching over the ship’s stern; fig. 1. 
shows an elevation of it in action; and fig. 2. a plan answering 
thereto. The invention consists of a top-mast, placed out of 
the ship’s stern, having planks fixed at the end of it, which go 
edgeways through the water; the mast is attached to the stern 
by a kind of joint or socket, on which, by proper guys, it ¢an be 
inclined in an angle, with the keel either larboard or starboard ; 
and will steer the ship as effectually as a proper rudder. 
To fit out a ship on this plan, the following materials must be 
collected and prepared as soon as the rudder is gone, or ex- 
pected to be lost. 
Ist. A spare top-mast AB, fig. 2. and two top blocks Ah, 
which must be securely lashed on at each end of it. 
2d. A top-sail-yard CD, which must have cleats, nailed se- 
curely upon it, forming a shoulder at the end C, which is to be 
kept on board; and at the opposite end must be framed a 
case eee, formed of pieces of oak plank, nailed firm to the yard, 
on each side, the left or foremast part being chamfered off and 
leaded: so that by presenting a narrow edge it may make the 
less resistance in passing through the water. 
As the taff-rail will not, in general, be found sufficiently strong 
to resist the force of the machine; a frame Admn, must be com- 
posed of substantial pieces of oak, and erected behind it, upon 
the deck ; it consists of two uprights mm, set up from a sill-x, 
which is spiked down upon the deck: and they support a 
rail p, which is firmly lashed to the taff-rail: and the whole is 
strengthened by three shores kk, stepped from the deck to the 
uprights mm: between these is supported a piece of oak ?, 
4+ inches thick, with a hole through it, of a proper size to re- 
ceive the end f, of the yard: the hole is leathered inside,’ in 
which the end f of the yard acts with perfect ease, and can swivel 
about in all directions ; the tapered end f of the yard is leathered 
also, that the whole may act easily. 
While these parts are preparing by one part of the crew, some 
should get the top-mast A athwart-ship, over her quarter, and 
make it fast by proper lashings; the others should be ready 
with the several tackles which rig it out, to give motion to the 
rudder when in the water. They are as follows: two principal 
guys, aa, madé of rope which is 5$ inches girt, and should be 
ef very good materials; they are to be made fast to the boards 
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