. 1*T4 Defcripthn of a EtiSoiict 



force of 40 pounds. If the diameter of the pifton, however, 

 be lefiened, and the cylinder, in order that it may hav« 

 the fame cubic content, be lengthened, and if a larger wheel 

 be added to gain more power, fomething will be loft iji re- 

 gard to time ; but it can be eafdy calculated to what greater 

 depth the machine may be-ufed, and how much the ftrength 

 of a man can accomplifh. The higher the machine is in pro- 

 portion to its diameter, the more fecurely will it remain per- 

 pendicular in the water, and the lefs danger will there be of its 

 being overturned ; becaufe the diver is then rearer the cen- 

 tre of gravity. That the fame advantage, however, may be 

 obtained with lefs expence, the wheel work, together with 

 the cylinder and pifton, may be omitted, and the machine 

 conftructed as far as the upper cover ; but it mull be fo 

 flirniihed with hooks for ballaft, that the diver, when he has 

 previoufly fcrewed on the pipe fattened to the machine and 

 placed himfelf on the ftage, may hang on ballaft, (tones or 

 other heavy fubftances, till it fink, and, by throwing them 

 away, may again afcend at pleafure. The machine in this 

 form is Ampler; and, in my opinion, to be preferred to 

 the conftruclion with the pifton, wheel and rack, which I 

 fhall endeavour to prove in as mechanical a manner as 

 poffible. 



" The ends of the pipe I m, which proceed into the ma- 

 chine, are fo applied that all the particles of air may gra- 

 dually proceed through the lungs. Should it, however, after 

 being ufed two hours, be no longer capable of fupporting life, 

 the diver mull afcend with his machine, and be conveyed to 

 the fhip or boat attending him, by means of the rope fatt- 

 ened to the ring n. He muft then fcrew oft' the pipe, open 

 the top 0, and, by means of" a pair of bellows fcrewed upon 

 the mouth-piece, expel the air from the machine, and blow 

 into it found atmofpheric air for further ufe*. 



r This is not an effectual way of removing the tainted air, which may 

 be more (imply, and at the lame time completely effoSted, by immerfing it, 

 when open, under water : on the pouring out of which afterwards, the 

 machine would be filled ymh atmofpheric air, EyiT. (( rp 



