CHUM N E YS: 25 
wood laid on, the fmoke would rife to A, turn over the 
edge of that plate, defcend to D, then turn under the edge 
of the upper plate, and goupthechimney. It was pretty 
to fee, but of no great ufe. Placing therefore the under 
plate in a higher fituation, I removed the upper 
plate C D, and placed it perpendicularly, fo that Pht") 
the upper edge of the lower plate AB came with-  ~ 
in about three inches of it, and might be pufhed farther 
from it, or fuffered to come nearer to it by a moveable 
wedge between them. The flame then afcending from 
the fire at E, was carried to ftrike the upper plate, made 
it very hot, and its heat rofe and {pread with the rarefied 
air into the room. 
I believe you have feen in ufe with me, the contrivance 
of a fliding-plate over the fire, feemingly placed to oppofe 
the rifing of the {moke, leaving but a {mall paflage for it, 
between the edge of the plate and the back of the chimney. 
It is particularly defcribed, and its ufes explained, in my 
former printed letter, and I mention it here only as ano- 
ther inftance of the traCtability of fmoke*. 
What is called the Staffordfhire chimney, affords an ex- 
ample of the fame kind. The opening of the chimney is 
bricked up, even with the fore-edge of its jams, leaving 
open only a paflage over the grate of the fame width, and 
perhaps eight inches high. The grate confifts of femicir- 
cular bars, their upper bar of the greateft diameter, the 
others under it {maller and fmaller, fo that it has the ap- 
pearance of half a round bafket. It is, with the coals it 
contains, wholly without the wall that fhuts up the chim- 
ney, yet the {moke bends and enters the paflage above it, 
the draft being ftrong, becaufe no air can enter that is not 
obliged to pafs near or through the fire, fo that all that 
the funnel is filled with is much heated, and of courfe 
much rarefied, 
D Much 
See Appendix, N° Il. 
PI 
