137 
FUR 
fqiiare feet of area. In calculating the proportions and 
diinenfioiis of'.vater regulators in general, the principle is, 
to allow the (pace around t he inverted chert eqtial in point 
of fiiperficial meafiirement to the area of the interior of 
the chert, that the defcending column of water may dif- 
place no more in the perpendicular afcent, than it is it- 
felf abfoliitely deprerted. If the area or fpace, in which 
the water rifes and falls, is only equal to half the area of 
the inverted chert, then for every foot of water which is 
deprelfed in the bottom of the chert, a coltimn of two feet 
will be raifed and maintained on the outfide. On the 
contrary, if the outfide fpace for water be equal to twice 
the area, th.en every foot of water deprerted in the chert 
will only elevate the external column fix inches. I.t is 
evident, therefore, from thefe general fads, that a con- 
iiderable latitude may at any time be alfttmed in con- 
rtruding the water regitlator, partictilarly in old eftab- 
lirtted works, wheie local circumftanceb and convenience 
Confine its fituation to one fpot. 
Where it is not inconvenient to ufe a high perpendicular 
column of water, the inverted chert may be increafed one 
half, double, or even triple, the fiiperficial meafurement 
of the outfide fpace ; fb that if the power of the blowing 
machine is equal to three pounds upon tiie fquare inch, 
the water in the cliert will be deprerted nearly three feet 
and a half, and raifed in the perpendicular column five 
feet three indies in the firft, feven feet in the fccond, and 
ten feet and a half in the lart, cafe. This plan, to fuit 
former ertablirtiments, may be adopted with conliderable 
modifications, always keeping in mind, that every foot of 
area gained upon the (urface of the water, is a ma¬ 
terial acquifilion to the equalifing powers of the regu¬ 
lator. 
One imperfedion, however, attends this w'ant of equi¬ 
librium on the two fpaces for the adion and re-adion of 
the water.—Whatever fpace the waters would fall, at 
the return of the rtroke, luppofing the inlide and outfide 
columns exadly balanced, would in this cafe be increaled 
one half, double, or triple. Again, where fituation does 
not admit of the perpendictilar column being raifed be¬ 
yond, or not even to the extent, of the deprelfion that 
takes place within the inverted chert, and where an ad- 
ditional fpace cannot be procured for an increafe of its 
■diameter, an inverted cheft of much lefs height than com¬ 
mon may be uled, loaded with a material of great weight, 
fuch as iron. The water in that cafe would dirtribute 
itfelf over the furface of the chert, inftead of rifing in per¬ 
pendicular height. 
But a ferious objedion is notwithrtanding ■ made to 
cherts or cylinders, where the edudion pipe approaches 
■within a rtiort fpace of the furface of the water; namely, 
water rifing in the pipes, and being conveyed along- with 
the air into the furnace. This may take place in two 
ways ; by an iiifenfible and uniform difeharge of water 
into the furnace, making the blart at the tuyere vilible, 
like the refpiration of the human body in a frorty day; 
■or fometinies in quantity, fufficient to hazard the dertruc- 
ticn of the furnace and buildings. The former is occa- 
fioned by the air from the edudtion pipe, at the com¬ 
mencement of the rtroke, impinging violently upon the 
lurface of the water, and raifing a portion of it in the rtate 
of fpray. This is fpeedily dillblved or entangled in the 
niafs of condeiifed air before the return of the next rtroke, 
and becomes exprelfed along with the blart into the fur- 
fiace. The other hazardous confequence is occafioned 
chiefly by undulation in the column of water, when the 
blowing machine is, by derangement or accident, working 
■under its proper power or number of rtrokes. In thele 
cafes, when the paiife at the end of the rtroke is pro¬ 
longed, an exhaurtion fonietimes takes place in the air- 
pipes, the water rifes and is carried in a ftream through 
the blowing-pipe into the furnace. The fame cafualties 
will alfo occur, if the furface of the water is upon a level, 
or nearly fo, witli the tuyere. 
VoL, VIII. No. 490, 
N A C E. 
In judicious eredlons this danger is mort carefully 
avoided ; the furface of water in the inverted cheft or 
cylinder is kept at leaft eight, nine, or ten, feet under the 
level of the tuyere, even at the lull period of return, when 
the water has rifen to its greateft height witliin. This 
precaution alfo enfures an advantage of much importance. 
A large fpace is obtained betwixt the top of tlie chert and 
the deprerted furface of tlte water; this becomes a fpa- 
cious relervoir for the condenfed air, and, by generating 
a confiderable portion of elarticity, prevents any violent 
perturbation upon the water at any period of the rtroke. 
The increafed diftance betwixt the furface of the water, 
and the pipe which condufls the air from the cylinder, 
has a complete tendency to prevent the elevation of the 
aqueous particles, and always enfures a quantity of air 
comparatively free from niotlhire. 
Tiie application of water regulators to blowing ma- 
chines, by Mertrs. Bolton and Watt, was foon followed 
by an attempt at further improvement, by the introduc¬ 
tion of tire air-vault; the principle of which was to form 
a receiver of fuch capacity, that the elarticity or fpring of 
the condenfed air would be fufficient to exprefs and equa- 
life the blart during the return of the flroke. To ertbet 
this, an immenfe magazine was requirtte ; to erebl whicli 
of any metallic fubftance would have been ruinoiifly ex- 
penfive, and, if cotiftrufted of wood, infiifficient for re. 
taining the air. It became therefore requirtte to try the 
experiment upon building, or by excavation from the 
folid rock. 
Air-vaults of this kind were conflru6led both at the 
Clyde and Muirkirk iron-works in Scotland, and a con- 
ftant current of air produced ; but nearly one half tlie 
quantity lifted by the air-pump efcaped through the walls 
and arclies of the building. This was made vifible by 
rubbing I'oapy water upon the external walls. At Devon 
iron works in Scotland, an air-vault was excavated from 
the folid rock, feventy-two feet long, fourteen feet wide, 
and thirteen feet high; equal to thirteen tlioufand feet of 
cubical meafurement. This immenfe excavation was 
made comparatively air-tight, by cauking the Teams and 
fill'uresof the rock, plaftering and then covering the whole 
witli alternate layers of pitch and clofe wove paper. This 
was the moll perfeifi: experiment ever tried upon the air- 
vault ; and if an opinion is to be formed of the perfection 
of the apparatus by the quantity of iron at one time ma¬ 
nufactured, a very trifling portion of air indeed muff have 
been loft. It has been frequently noticed in Scotland, 
that at works where the materials were in any degree 
fimilar, three thoufand to three thoiifand five hundred 
cubical feet of air per minute will, in the courfe of a 
week, produce from thirty to thirty-five tons of pig-iron, 
whatever may be the denlity at which it is thrown into 
the furnace. In both thefe ways lias the air-vault beeir 
tried ; but with fuch indifferent confequences as to its fu- 
periority, that the plan feems now to be given up. 
Several other modes of conliruCtion for the blart-ftir- 
nace have of late been tried, but without even reaching 
the advantages of the one already deferibed. The verti¬ 
cal feCfion of a very curious furnace of this kind, cut 
acrofs from the top of the borties, is exhibited in the pre¬ 
ceding engraving at figure 5. d'he conliruCtion is truly 
fingiilar; and from this alone great advantages were ex¬ 
pected to relult. The originality of the principle conlirts 
in the double fquare, or throat; one immediately above 
the hearth, which is not (hewn in this figure, and another 
half way up the cone, four feet in diameter, as reprefented 
in the plate at A.—B, tlie top of the borties, where the 
leCtion or cone is cut oft', twelve feet in diameter. C, an 
inferior diameter of ten feet, previous to the formation of 
the throat at A. D, the top of the fecond row of borties, 
of the fame diameter as B. E, the furnace inoutli, or 
termination oi the fecond cone, four feet diameter, and 
proportioned to A. F, the funnel top for carrying oft' 
the flame occafioned by the blart, fo as rot to interfere 
Nn witfe 
