58 DESCRIPTION or a 
Whoever would repeat this experiment with fuccelsy, 
muft take care that the partA,, B, of the fhort tube be quite 
full of burning coals, fo that no part of the {moke may 
defcend and pafs by them without going through them,, 
and being converted into flame; and that the longer tube 
be fo heated. as that the current of afcending hot air is 
eltablifhed in it before the things to be burnt are laid on 
the coals; otherwife there will be a difappointment. 
It does not appear either in the Memoirs.of the Academy 
of Sciences, or Philofophical Tranfactions of the Englifh 
Royal Society, that any improvement was ever made of 
this ingenious experiment, by applying it to ufeful pur- 
pofes. But there is a German book, entitled Vulcanus . 
Famulans, by Joh. George Leutmann, P. D. printed at Wir- 
temberg in 1723, which defcribes, among a great variety 
of other ftoves for warming rooms, one which feems to 
have been formed on the fame principle, and probably 
from the hint thereby given, though the, French experi- 
ment is not mentioned. This book being {carce, I have 
tranflated the chapter defcribing the ftove, viz. 
“ Vulcanus Famulans, by John George Leutmann, P. D.. 
“ Wirtemberg, 1723. 
€e NG sia BN pts ce Weld 
“On a ftove, which draws downwards. 
* Here follows the defcription of a fort of ftove, which: 
“can eafily be removed and again replaced at pleafure. 
“This drives the fire down under itfelf, and gives no. 
«“ f{moke, but however a very unwholefome vapour. 
“In the figure, A is an iron veflel like a fun- 
“ nel, in diameter at the top about twelve inches, 
“at the bottom near the grate about five inches ; 
“its height twelve inches. ‘This is fet on the barrel C, 
“ which is ten inches diameter and two feet long, clofed 
66 at 
Plate Il. 
Figure 20. 
