Improvement in Naval Arch'ileclure, &fc, 437 



pie of wliich Messrs. Trevitliick and Dickinson have availed 

 themselves. Their valve or valves are attached to a rod in 

 the hollow trunk, vvh'ich rod being coomcted with ihe ann 

 of the steam engine receives a reciprocating motion like a 

 piston, and thn? opens and shuts 'he valves alternately. If 

 the hollow trunk be of sulEcient dimensions, it is evident 

 that its contents will have so much inertia or resistance as 

 to receive but little velocity from the piston, and that the 

 surplus power must carry the vessel forward in an opposite 

 direciion. 



If the hollow trunk be made moveable and attached to 

 the rowing arm. and there be a stop within, of the nature 

 of a valve, to shut against the stroke and open with the 

 return, the effect will be the same as with the former ar- 

 rangeir.ent, but the machinery would probably be more 

 cumbrDus and apt to get out of repair. 



Ill, Sliding iulndar Masts, made of Ircn. and so con- 

 structed that the upper ones slide into the loivey, in a 

 Marnier soinewhat like a Pocket Telescope. 

 '' A hollow iron mast of the thickness of half an inch, 

 and of the same height and diameter as a wooden mast, 

 will be much lighter, considerably stronger, much more 

 durable, less liable to be injured by shot, and can be easily 

 repaired, even at sea. It will weigh only 12 tons, and at 

 Abl. per ton will not cost n)ore than 540/., while its 

 strength will be nearly fifty per cent, over that of a woodca 

 mast that weighs 23 tons, and costs nearly 1,'200Z. 



•* This mast is made to strike nearlv as low as the deck, 

 to ease the ship in a heavy sea — Wooden n)asts are, in 

 such circumstances, obliged to be cut away. Ships fur- 

 nished with these masts will not, like others, be expoied 

 to the risk of receiving damage from lightning. The iroii 

 mast being itself an excellent conductor, hv using an iron 

 bolt from the bottom of the mast, throuc^ii the kelson and 

 the keel, the electric matter vvill he conducteti tlnoneli the 

 bottom of the ship into the water, v/nhoui injury to the 

 ship. 



*^ Yards and bowsprits may also be made of wrought 

 iron, at the same proportion of strength and expense as 

 the mast. Chain shrouds and stays made of iron * may 



• since fliis prospectus was first circulated (Feb. 10, r^SOf),) we have 

 learnt tiiat the idea of emploviiii/ iron rig-^in;^ lias .ictiia'ly luvii i arricti into 

 effect by a l.Icut. Krown ; anj :i vessel rigged in thi>) manner, bnt \vit!> uocdcn 

 niakts, is now to be teen in tiie West Imlia Duclc. 'J'he lirst projioial. Unw< 

 ever, that wc have licard of for usiiijf metal in' rig^ging wa> iVi'ia i\Ir. 'I'llJoch, 

 ^li iheytif 1801. Phil. Mag. vol. xxi. p. 108. 



also 



