In September 1786, John Gardiner (1737–1793) of Boston sent Academy President James Bowdoin a drawing and description of a ferry in Bethlehem, Pennsylvania, designed by Nicholas Garrison, a member of the Moravian Brethren. The ferry used a rope or cable and the river’s current to move the boat back and forth, and the design could be upscaled for larger crossings through a series of blocks and pulleys.
In his letter, Gardiner wrote that the drawing itself “sufficiently explains the easy Transfir [sic] of the Boat over the River, and, if properly attended to, may be of general use to mankind.” He later supplemented the drawing with a description of the design, providing additional details on how to employ the system for a wider body of water.
“Suppose a Ship at Anchor in a River with a strong stream, If the helm be put a port, the Vessel will shear to the Starboard Shore, as far as her cable will let her. The Rudder is not the Cause, but the Stream; for if I fasten a Rope, or Spring, to the Cable and fasten it to her Stern, letting out a little Cable, she will Shear in like manner without the Rudder.
Again, Suppose a River a Mile wide (which is too wide for a Rope) I’ll get a Chain the Length of the width of the River, and one End being fastened to a sufficient Anchor, place the same in the middle of the River, its whole Length & more, above the intended Ferry, and take a sufficient Number of Boats (say 12) to bear up the said Chain. . . . To the other End of the Chain which will be at the last Boat, I would fasten a Rope or Pendant of 5 or 6 Fathom ^long, and to that a Guy to which a Flat or Scow is fastened . . . if I draw in 2 or three fathom of one of them, or let out as much of one of them, the one Guy becomes so much shorter or longer than the other and will put the Flat in another position and in motion.”
(Letter from Nicholas Garrison to John Gardiner, January 4, 1787)