Air Vault. — Hydraulic E?tgine. iij 



In order to illuftrate what is faid above, a ground plan of the air vault and furnaces of 

 the Devon Iron Works is given in Plate V. ; of which the explanation follows : 



Explanation o/" Fig. I. Plate V. 

 A The air vault, formed by a mine drove in the folid rock of coarfe grained freeftone. 



B The blowing cylinder. 



C The pipe that conveys 'the air from the blowing cylinder to the air vault. 



D The eduftion pipe that carries the air from the air vault to the iron wind cheft. 



E The iron wind cheft, (about zi feet cube), in which is inferted a wind-gauge, re- 



prefented in fig. 3. 

 F F The two blow pipes for each furnace, which terminate in apertures of 3^ inches 



diameter at the tweers of the furnaces. 

 G G Tlie two blaft furnaces, placed in two pits funk in the folid rock. 

 H H The timps of the furnaces from whence the caft-iron is run off into the calling 



room, L L. 

 O The door to give occafional admittance into the air vault. 



M The excavation, in which is placed the blowing machine. 



Explanation of Fig. 2. 

 A The end of the wind-guage, (about 12 inches long), which is open to the at- 



mofphere, being half filled with quickfilver. 

 B The end that is inferted in the iron wind cheft, and expofed to the preflure of the 



condenfed air of the air vault. 



IV. 



Apparatus for making the Hydraulic Engine at Schemnitz work itfelf without Attendance. By 



. Mr. JoHvi Whitiey Boswell. 



H. 



To. Mr. NICHOLSON. 

 SIR, 



May], 1800. 



.AVING laft fummer met with a defcription of an engine, fimilar in its principles to 

 the hydraulic machine of Schemnitz, (of which there is an account in the Number of your 

 Journal *, in which you did me the honour to infert my communication of a new venti- 

 lator) ; I was induced to contrive a method for making it work itfelf, as wpU from the 

 utility of fuch an invention, as from its being obvious at firft fight that it was very 

 pradlicable. 



* Vol, IV. p. 1$. 



From. 



