754 REPORT—18638. 
made the following examination of the temperatures of different furnaces 
working with close tops :— 
Clarence No. 5 furnace, 48 feet high, making No. 4 iron. 
hm 
Full... ane Soh enor eo Pn Pas of besiirs gases, BS F. 
2 25 
Put on 75 cwt. materials 2 35 ae: oo qe 
Same furnace, making Nos. 2 and 3 iron. 
hm 
ah. ap ... 2 © Temperature of escaping gases, 710° F. 
2 10 do. do. 840 
2 20 do. do. 940 
Put on 25 cwt. materials 2 30 do. do. 710 
Walker No. 4 furnace, 42 feet high, making No. 4 iron. 
hm 
ols: . cae «. 2 © Temperature of escaping gases, Soe F. 
2 10 do. do. 800 
Introduced 33 c. materials 2 20 do. do. 670 
Middlesboro’ No. 2 Sains 42 feet high, making white iron. 
h 
Mallet 22. = sya eee, Fs © Temperature of escaping gases, 519° F.. 
2 20 do. do. 960 
Put on go cwt. materials 2 30 do. do. 469 
The mean temperatures will be as follows :— 
Clarence, making No. 4 iron... ads - re ey fee 
Do. do; . Nova 825 
The mean temperature of the tube ° conveying the ape from four 
furnaces was 808 
Walker, making No. 4 iron oat Ses a8 eS «390 740 
Middlesboro’, making white iron... see ane sat oe ee 
The object of these figures is to show that, taking Scheerer’s statement as 
our guide, the whole of the furnaces alluded to are working at a loss. 
It is obvious that there is an escape of heat capable of preparing an addi- 
tional quantity of material for treatment in the reducing and fusing zones of 
the furnace. The obvious method of making this heat available is by in- 
creasing the height of the furnace itself. This, however, has its limit, vary- 
ing probably with the nature and size of the materials used. If, for example, 
the fuel is easily crushed, or the “ mine” is small, or easily rendered so, then 
the altitude of the column containing it must not be above that which will 
permit the blast to enter freely and preserve, as far as possible, an equal tem- 
perature over every horizontal section or zone of the materials. 
It is more than probable that the limits of extreme height have been already 
reached by experience in other localities, the ironmaster there being guided 
by the peculiar characteristics of his own minerals. 
The iron-furnaces in Cleveland work under a totally different set of cireum- 
stances from those of Staffordshire, for instance, where the coke is friable and 
the “ mine” small. Our coke is endowed with great hardness and capability of 
resisting pressure ; and our ironstone, worked in great blocks, is sufficiently 
large to permit a free passage of air through a much higher column than 
otherwise would be the case. 
Messrs. Bolckow and Vaughan have actually put this to the test of prac- 
tical proof by erecting a furnace 75 feet high. Upon one occasion, in making | 
No. 4 iron, the gases were escaping at a temperature of 467° just after 
