and the Economy of Fuel. 159 



Fig. 15 and Fig. 16 show, on an enlarged scale, one 

 of the four pieces of brass by which the circular plate of 

 the register is kept down in its place. 



In constructing these register doors, and in general 

 all iron doors for fire-places, great and small, the door 

 should never shut in a rabbet or groove in the frame, 

 but should merely shut down on the front edge of the 

 frame, which edge, by grinding it on the flat surface of 

 a large flat stone, should be made quite level to receive 

 it. If this be done, and if the plate of iron which con- 

 stitutes the door be made quite flat, and if it be properly 

 fixed on its hinges, the door will always shut with facility 

 and close the opening with precision, notwithstanding 

 the effects of the expansion of the metal by heat ; but 

 this cannot be the case when the doors of fire-places are 

 fitted in grooves and rabbets. 



Where the heat is very intense, the frame of the 

 door should be made of fire-stone ; and that part of 

 the door which is exposed naked to the fire should be 

 covered either with a fit piece of fire-stone, fastened to 

 it with clamps of iron, or a sufficient number of strong 

 nails with long necks and flat heads, or of staples, being 

 driven into that side of the plate of iron which forms the 

 door which is exposed, should be covered with a body 

 about two inches thick of strong clay mixed with a due 

 portion of coarse powder of broken crucibles, which 

 mass will be held in its place by the heads of the nails 

 and by the projecting staples. This mass being put on 

 wet, and gently dried, the cracks being carefully filled 

 up as they appear, and the whole well beaten together 

 into a solid mass, will, when properly burned on by the 

 heat of the fire, form a covering for the door which will 

 effectually defend it from all injury from the fire ; and 



