151 
Iran, 
14th!y, As the charcoal requires time to be decompos- 
ed, and the iron ore requires time to be metallized and 
carbonated, the size and slope of the boshes should be 
|j regulated by attentive observation of the process in all its 
Course, during the first period of blast : for ore of one 
kind may be carbonized quicker than ore of another kind, 
and therefore may be permitted to descend more speedily 
(in comparison.) This must be the result of close and 
| local attention, 
15thly, I am not qualified to give an opinion, but I 
would suggest, that in Pennsylvania generally, there has 
been error, rather in giving too little than too much blast* 
Also, that a slight inclination of the blast upward rather 
than an horizontal stream, is to be preferred. For, in the 
latter case, there is (as I think) danger of cooling the slag, 
or oxygenating the metaL Also, whether the same quan- 
tity of air, would not answer a better purpose from tw o 
j pipes in opposite directions than from one ? 
16thly, It appears, that pit- coal or coak furnaces, re- 
quire to be higher, and require also a greater blast to con- 
sume and decompose the fuel than charcoal furnaces ; 
j and the ore requires a longer time to be metallized than 
with wood charcoal : I have sometimes thought the 
1 Pennsylvania furnaces are somewhat higher than neces- 
sary. I have measured the plates in Jars, and find the di- 
ll rnensions of various furnaces as under. 
Ground Width at Height f row 
plan . 
the boshea. the hearths 
Iron furnace at Eisenhartz 
13 
8. 
3 
33 
Treyback, in Carinthia 
16 
4. 
— 
22 
John-Georgen-Stadt, 1 
in Saxony 5 
"29 
5. 
- 
21 
Sweden 
25 6 
7. 
25 
Laurwig, in Norway 
30 
8. 
— 
30 
'The above are French feet,. 
which 
) are 
to 
the English 
3 $ 114 to 107. 
