General Principles and ConJlruSlion of a Sub marine Vefftl. ijt 



downward, or continue at any particular depth, with an oar, placed near the top 

 of the vefl'cl, formed upon the principle of the fcrew, the axis of the gar entering the 

 vefll-l ; by turning the oar one way he raifed the veflel, by turning it the otlier way he 

 deprefll'd it. 



A glafs tube eighteen inches long, undone inch in diameter, ftanding upright, its upper 

 end clofed, and its lower end, which was open, fcrewed into a brafs pipe, through which 

 the external water had a pafiage into the glafs tube, ferved as a water-gauge or barometer. 

 There was a piece of cork with phofphorus on it, put into the water-gauge. When the 

 veflel defcended the water rofe in the water-gauge, condenfing the air within, and bearing 

 the cork, with its phofphorus, on its furface. By the light of the phofphorus, the 

 afcent of the water in the gauge was rendered vifible, and the depth of the veflel under 

 water afcertained by a graduated line. 



An oar, formed upon the principle of the fcrew, was .fixed in the forepart of the veflel; 

 its axis entered the veflel, and being turned one way, rowed the veflel forward, but being 

 turned the other way rowed it backward ; it was made to be turned by the hand or 

 foot. 



A rudder, hung to the hinder parfpf the veflel, commanded it with the greatefl; eafe. 

 The rudder was made very elafl:ic, and might be ufed for rowing forward. Its tiller was 

 within the vefl"el, at the operator's right hand, fixed, at a right angle, on an iron rodj 

 which pafled through the fide of the veflel; 'the rod had a crank on its outfide end, which 

 commanded the rudder, by means of a rod extending from the end of the crank to a kind 

 of tiller, fixed upon the left hand of the rudder. Raifing and deprefling the firft men- 

 tioned tiller turned the rudder as the cafe required 



A compafs marked with phofphorus dire£ted the courfe, both above and under the 

 water ; and a line and lead founded the depth when neceflary. 



The internal fhape of the veflel, in every pofllble fe£bion of it, verged towards an- 

 ellipfis, as near as the defign would allow, but every horizontal fedlion, although ellip- 

 tical, yet as near to a circle, as could be admitted. The body of the veflel was made ex- 

 ceedingly flrong ; and to flrengthen it as much as poflTible, a firm piece of wood was- 

 framed, parallel to the conjugate diameter, to prevent the fides from yielding to the great 

 preflure of the incumbent water, in a deep immerfion. This piece of wood was alfo a 

 feat for the operator. 



Every opening was well fecured. The pumps had two fets of valves. The aperture at 

 the bottom, for admitting water, was covered with a plate, perforated full of holes to 

 receive the water, and prevent any thing from choaking the pafiage, or ft:opping the valve 

 from (hutting. The brafs valve might likewife be forced into its place with a- fcrew, if 

 neceflary. The air pipes had a kind of hollow fphere, fixed round the top of each, to 

 fecure the air-pipe valves from injury : thefe hollow fpheres were perforated full of holes 

 for the paflage of the air through the pipes : within the air-pipes were fhutters to fecure 

 ihcm, fliould any accident happen to the pipes, or the valves on their tops. 



Whcrere* 



