43. EXPLANATION. 



E The iron wind cheft, (about 27 feet ci;be), in which 



is inlerted a wind-gauge, reprefented in fig. 3. 



F F The two blow-pipes for each furnace, which termi- 



nate in apertures of 37 inches diameter at the 

 tweers of the furnaces. 



G G The two blait 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 ma- 



chine. 



Explanation of Fig. 3. 



A The end of the wind-gauge, (about 1 2 inches long), which 

 is open to the atmofphere, being half filled with quickfil- 

 ver. 



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

 to the preffure of the condenfed air of the air vault. 



III. 



