AYP)P EN -Di 1X. 
NOTES ror roe LETTER veron CHIMNEYS. 
1a een 2 
HE lateft work on architecture that I have feen, is that 
entitled NursHELLs, which appears to be written by 
a very ingenious man, and contains a table of the propor- 
tions of the openings of chimneys ; but they relate folely 
to the proportions he gives his rooms, without the {mall- 
eft regard to the funnels. And he remarks, refpedting 
thofe proportions, that they are fimilar to the harmonic 
divifions of a monochord*. He does not indeed lay much 
ftrefs on this; but it fhows that we like the appearance of 
principles ; and where we have not true ones, we have 
fome {atisfaction in producing fuch as are imaginary. 
N° II. 
"THE defcription of the fliding plates here promifed, 
and which hath been fince brought into ufe under va- 
rious names, with fome immaterial changes, is contained. 
in a former letter to J. B. Efg. as follows : 
To J. B. E/g. at Bofton, in-New-England, 
Dear Sir, London, Dec. 2, 1758. 
I HAVE exccuted here an eafy fimple contrivance, that 
I have long fince had in fpeculation, for keeping rooms 
warmer 
* «© Tt may be juft remarked here, that upon comparing thefe proportions with thofe arifing 
*« from the common divifions of the monochord, it happens that the firft anfwers to unifon, 
** and although the fecond is a difcord, the third anfwers to the third minor, the fourth to the 
«« third major, the fifth to the fourth, the fixth to the fifth, and the feventh to the ottave.”” 
NuTsuEtys, page 85. 
