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at Erskine House. 

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ft. 10 



30 ft. 



is carried up, opposite the furnace, to within a few inches of 

 the surface, with a 2-inch cavity (b). As the heat rises above 

 the surface, it enters the wide space (c) ; from whence it is 

 immediately divided through the wall. I have, however, a 

 yard or two of the wall, at the warm end of the under flues, 

 a little thicker (d). 



As flued walls are always warmest towards the top of the 

 flues, the idea struck me, that if one, two, or more bricks 

 (according to the depth of the flues) were built across the 

 upper ends, as shown at e, they would, by confining the draught 

 of smoke towards the bottom of the flues, tend to equalise 

 the heat in them. This did not answer my expectations ; for it 

 retained too much of the heat in the under and third flues, 

 which caused a deficiency in the second and upper one : 

 but having bricks run across the upper part of the cooler 

 ends of the second and upper flues, as shown in the sketch 

 {e e), is of considerable advantage, as a means of retaining the 

 heat in these flues ; and making the heat throughout more 

 equal and uniform, and requiring less fire : indeed, walls upon 

 this construction never require large fires. 



If it were desirable to warm the upper part of the wall 

 only, by withdrawing the damper, and applying a small 

 fire, this would be accomplished without warming the lower 

 part of the wall. Depth of flues, 2 ft. 6 in., 2 ft., 2 ft. 3 in., 

 and 1 ft. 6 in. ; width, *l\ in. Bottom of lowest under flue, 

 1 ft. from the surface ; top of upper flue, within 7 in. of the 

 coping ; the thickness of the wall, about 1 ft. 9 in. 



By reducing the open space in the flued wall (a) to about 

 30 square inches, the damper may be dispensed with ; but, 

 by retaining it, the heat can be regulated according to cir- 

 cumstances. 



