360 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[October, 



Fig. T). — Plan showing the Ash-pit and Hot Air-flue. 



Fig. 6. — Longitudinal Section through Centre uf Oven. 



A ROASTING OR BAKING OVEN. 



Sir — In answer to your call for communications, I feel as a con- 

 stant reader that it is my duty to contribute occasionally my mite, I 

 will therefore now address you on the subject of Kitchen Fire-places. 



Roasted meat is a favourite mode of cookery in England, although 

 not quite so much in vogue as it was previous to 1815. Kitchen fire- 

 places are constructed chiefly for this purpose— but the consumption 

 of fuel is far greater tlian is required to effect the object in view, con- 

 sequently there is a waste of material, and an unnecessary incon- 

 venience from excessive heat. Tlie latter is more particularly felt in 

 town-built houses, in which the kitchen is generally on the basement 

 floor. Here the heated air ascends and fills the house with offensive 

 effluvia. Another inconvenience arising from open kitchen fire-places 

 is, that the boiling process cannot be regulated with any certainty. It 

 is a well known fact that violent ebulition is not only not necessary, 

 but is even injurious, and that simmering is the extent required espe- 

 cially ni soup-making. Now this medium can never be attained on 

 open fire-places. I would pro]50se to put an end to this waste of fuel, 

 and annoyance to all parties, from the cook upwards, by doing away 

 witli open kitchen fire-places entirely, and substituting a mode of 

 roasting which would be more effectual, and under a perfect controul. 



The difference between meat roasted before an open fire-place, and 

 baken in an oven, consists in this, that in the one case it has been ex- 

 posed to a change of air, and in the other case the meat has been 

 dressed in the same air, and in a confined space. Now if we can 

 construct an oven which shall have a constant current of lieated air 

 passing fhrougli it, I conceive that meat can be more etfectually roasted 

 in it than it could be before an open fii-e-place, and that such an oven 

 will be more convenient in all respects, more economical, and not liable 

 to the objections which I have hinted at as consequent on open fire- 

 places. 



Annexed are six drawings of a roasting or baking oven which I de- 

 signed in 1833, and I will now proceed to explain its mode of action. 



Tlie boiler B to be made of cast-iron 2' 0" x 1' 9" X 1' 0" having 

 an opening into it on the top of 6" diameter, for the purpose of clean- 

 ing it out, and for receiving a steaming vessel for cooking vegetables, 

 &c., a cock to draw off boiling water, and a pipe to supply cold water 

 from a small cistern C, having a ball cock or other contrivance, so that 

 the supply may Ije self-acting. The upper surface of this boiler forms 

 the plate under the oven door. 



The furnace is placed under the boiler. The smoke flues S pro- 

 ceed horizontiilly by two openings, eacli 0" x fj" on the level of the 

 7th and 8th courses of brickwork, (from the floor line), inclining to the 

 right and left until they clear the hot-air flue A ; here they rise per- 

 ]iendicularly to the level of the tenth, eleventh, and twelfth courses, 

 passing on each side of the oven, and separated from it by 4 inches of 

 brickwork, until they reach the cast-iron frame of the oven door, which 

 is placed on the boiler; here they again rise, and they ultimately join 



in one flue 9" X 9" over the centre of the door, and under the damper 

 S. The opening into the furnace 6" X ^" is by a cast-iron door in 

 which is an opening of 2" x 1" having a sliding shutter, by which it 

 may be partially, or wholly closed. 



The hot-air flue A 6" X 6" enters from the ashpit, immediately 

 under the bearing bar, and proceeds horizontally on the level of the 

 third and fourth courses, until it clears the back of the oven. Here it 

 rises perpendicularly until it reaches the fourteenth course tand a 

 part of the thirteenth), where it branches to the right and left imme- 

 diately over the smoke flues, and separated from them by a tile. The 

 joint between the tile to be protected by a piece of slate or thin iron, 

 to prevent any smoke from rising into the hot-air flues. These flues 

 proceed horizontally until they reach the side of the oven near the 

 door, where they are admitted into the oven by two openings 0" X 4" 

 each, the upper part of the openings being on the level of the spring- 

 ing. 



The hot-air makes its exit at the back of the oven, close under the 

 soffit of the arch. From thence it may be carried up into a drying 

 closet, or the hot-air may be made available for any other useful pur- 

 pose. 



The entrance into the ashpit may be closed partly or wholly, by 

 means of the cast-iron door having an opening in it of 2" X 1", and a 

 sliding shutter, similar to that of the furnace door. 



According to this mode of construction the smoke never enters the 

 internal part of the oven; but when the gross particles of the coals 

 have been carried off through the smoke flues, and the fire burns bright 

 and clear, the action of the furnace may be reversed by pushing in 

 damper of the smoke flue S, opening the damper of the hot-air flue A, 

 closing wholly the ashpit door, and opening the shutter of the fumace 

 door. By these means nearly the whole of the heat produced by the 

 combustion of the fuel will be carried into the internal part of the 

 oven, through the hot-air flues. 



The hot-air should come in contact with every 

 part of the surface of the meat, both upper and 

 lower, and therefore the meat ought to be sup- 

 ported on the points of iron crows feet of this .^^^ 



shape. By these the whole apparatus of spits, r^ • 



smoke-jacks, &c., would be superseded. 



Should other additional contrivances be wanted in large establish- 

 ments for stewing, simmering, or boiling operations, hot plates and 

 confectioners furnaces may be advantageously introduced ; but in all 

 these cases the means of ventilation immediately over them should be 

 provided, so that the miwholesome fumes may escape through flues 

 into the open air. 



I am. Sir, your humble servant, 



Robert Thomson, Lieut.-Col., R.E. 



Dover, Uth July, 1839. 



