“The [third figure] presents the same objects in perspective; to which are now added two masts I K, placed obliquely on that Boat which forms the Head of the whole vessel. This obliquity is useful when the boat is drawn from one side only; but is injurious where the traction takes place indifferently on both sides: so that I should not, now, advise the use of this method—which indeed, I have avoided in [fig. 4] of this [Plate].”
“In every case, each of the masts carries a pulley near I K, over which passes a rope, the ends of which are fastened to the masts by proper brackets, near the deck: and to the middle of this rope is fastened the track rope L, by which the horses draw the Boat along. By these means the vessel is steered either to or from the land: for if the knot of the track rope is brought near the mast I, the Boat (which as before observed is the head of the whole vessel) veers towards the horses; and the contrary when the knot is drawn towards the mast K: both which effects are rendered the more prompt and decisive, by the use of the lee boards K M, the nature and use of which are already fully known.”
“But there are cases in which, from its great length, this Serpentine Boat would require a particular direction, for some intermediate point between its extremities; as although, in theory, every separate part ought to pass through the same water, yet in canals or rivers much bent, this may not invariably take place; and then a rudder would be useful, even in the middle of the vessel. I have therefore placed a pair at P R, [fig. 3]. Their motion is a vertical revolution, round a horizontal centre; and as they are formed obliquely to the sides of the Boat, when one of them is plunged into the water, it tends to drive the Boat in a sidewise direction: and if at any time it should be desired to stop the whole vessel, both rudders would be plunged at once into the water, when they would greatly contribute to that effect.”
“The [fourth figure] in this [Plate 18], presents a general view of the vessel, comprising five articulations, (or Boats) besides the head and stern—which latter would fit each other without any intermediate parts, and form a Boat alone. Nor do these five parts by any means limit the useful number: but the Plate would not have contained more, unless on a scale too small to be distinctly understood.”