Its principal 
parts. 
Its profit to 
the publick. 
i 74 NATURAL HISTORY 
Explication of the principal members of the fire or fleam-engine, 
Plate xix. Fig. i. and n. 
A, fouth front of the fire-engine houfo ; B, triangle for tend- 
ing the engine pumps, ©A. C, arch for the main bob to play in ; 
D, coal-houfe and fire-place ; E, capftan, and cable for the trian- 
gle ; F, Balance-bob to afiift the draught ; G, the bell. 
Fig. ii. H, feCtion from the weft; I, fouth end of the main 
bob ; K, main chain to draw up the water from the bottom ; L, 
end of the balance-bob, marked F, in Fig. i ; M, a fmall chain 
drawing from the adit to a ciftern, a ; N, force-pump to fupply 
the ciftern, b, for the boiler T, Me. ; O, north end of the main 
bob ; P, the cylinder ; Q, the planchings of the houfe ; R, the 
eaftern door ; S, pipes to let out the air and fteam from the cylin- 
der ; T, the boiler which fupplies the fteam ; U, the damper, to 
moderate the fire ; W, the fire-place ; X, the afhes pit ; Y, the 
axis of the main bob. 
Before we conclude this feCtion, let it be obferved, that the people 
of Cornwall are not the only gainers by the introduction of this 
ufeful engine ; the government participates the profit, and indeed 
without hazard : it may not be amifs therefore here to take a fhort 
view of the advantage to the publick revenue arifing from the ne- 
ceffary materials ufed in our Cornifh mines worked now by the fire- 
engines, fuch as ropes, candles, timber, powder, iron, coal, Me. 
the duties of which, together with the profit of four fhillings per 
hundred weight for all tin railed in the three following mines, Hand 
as follows: 
The neat gain to the government from the mine (moftly of cop- 
per) called the North-Downs, in the parifh of Reddruth, in one 
month, (the drawback of the duty on coals confumed in the two 
fire-engines, amounting to forty-nine pounds fifteen fhillings and 
fix-pence, being firft deduced) amounts to four hundred and feventy- 
nine pounds five fhillings and fix-pence. 
In the mine called Pitt-louarn, Refnorth, and metal-works, the 
neat gain to the government (the drawback on coals confumed in 
two fire-engines, amounting to fixty-two pounds four fhillings and 
five-pence, being firft deduced) is two hundred and eighteen pounds 
and four-pence per month. 
In Polgooth mine, in the parifh of St. Mewan, the neat gain 
to the government (the drawback on coals confumed in one 
fire-engine, amounting to twenty-foven pounds eighteen fhillings 
and four-pence, being firft deducted) amounts, in one month, 
to two hundred and twenty- fix pounds foven fhillings and 
four-pence. 
“ Thefo 
