1886.] on the Principles of Domestic Fireplace Construction. 346 



heat slip tliroiigli it up the chimney, gives very little back to the 

 room, and chills the fuel. On this point also Rumford speaks very 

 strongly. " The best materials I have hitherto been able to discover 

 are firebrick and common bricks and mortar." " The fuel, instead 

 of being employed to heat the room directly or by the direct rays 

 from the fire, should be so disposed or placed as to heat the back and 

 sides of the grate, which must always be constructed of firebrick or 

 firestone, and never of iron or any other metal." (III. 345.) 



EuLE III. " The firebrick back shoidd lean over the fire, not lean 

 away from it," as has been the favourite construction throughout the 

 kingdom. The lean-over not only increases the power of absorbing 

 heat from rising flame — otherwise lost up the chimney — but the 

 increased temperature accumulated in the firebrick raises the tempera- 

 ture of gases to combustion point, which would otherwise pass up 

 the chimney unconsumed, and thus be lost. Eumford discovered 

 accidentally the value of this " lean-over," and at once realised its 

 immense importance. He does not, however, seem to have carried out 

 his intention of working out for general adoption this form of back. 



He first of all condemns to alteration all firebacks which lean 

 away from the fire. " It frequently happens that the iron backs of 

 grates are not vertical, but inclined backwards. Where the grates 

 are wide, and can be filled up with firebrick, the inclination of the 

 back will be of little consequence, since, by making the firebrick in 

 the form of a wedge, the front may be made perfectly vertical, the 

 iron back being hid in the solid work of the fireplace. If the grate 

 be too shallow to admit of any diminution, it will be best to take 

 away the iron back entirely, and cause the vertical back of the 

 fireplace to serve as the back to the grate." (III. 521.) 



He next describes his discovery of the value of the " lean-over": — 

 " In this case I should increase the depth of the fireplace at the 

 hearth to 12 or 13 inches, and should build the back perpendicular 

 to the height of the top of the burning fuel, and then, sloping the 

 back by a gentle inclination forward, bring it to its proper place, 

 that is to say, perpendicularly under the back part of the throat of the 

 chimney. This slope (which will bring the back forward 4 or 5 

 inches, or just as much as the depth of the fireplace is increased), 

 though it ought not to be too abrupt, yet it ought to be quite finished 

 at the height of 8 or 10 inches above the fire, otherwise it may 

 perhaps cause the chimney to smoke. 



" Having been obliged to carry backward the fireplace in the 

 manner here described, in order to accommodate it to a chimney 

 whose walls in front were remarkably thin, I was surprised to find, 

 upon lighting the fire, that it ajDpeared to give out more heat into 

 the room than any fireplace I had ever constructed. This effect was 

 quite unexpected ; but the cause of it was too obvious not to be 

 immediately discovered. The flame rising from the fire broke 

 against the part of the back w^hich sloped forward over the fire, 

 and this part of the back being soon very much heated, and in 



