The 20th Imrovement

Consists in making the lower masts of large ships in two or more lengths of wood, inserting the small end of one length into a deep square socket of another length, and then placing a long wrought-iron cylinder over the joint -- screw-bolting the upper and lower ends of the cylinder to the wood, to prevent the mast from twisting.

An iron cylinder placed round the hold-part of every lower-mast, would serve the doubly useful purpose of encasing the mast without taking up much room, and of enabling the mast to be lengthened, should the mast-head decay or be carried away.

Shipwreck and Collisions at Sea greatly prevented by Christophers' Patent Improvements in Naval Archtecture. With four plates.
London: J. Olliver, 59, Pall Mall; P. Richardson, 23, Cornhill. Liverpool: Deighton & Laughton. M.DCCC.L. 8vo, (4), 112 p, 4 pl.

Transcribed by Lars Bruzelius

Sjöhistoriska Samfundet | The Maritime History Virtual Archives.