Observations on the ventilation of rooms; on the construction of chimneys; and on garden stoves / Principally collected [by R. Willan] from papers left by the late John Whitehurst.

  • John Whitehurst
Date:
1794
Catalogue details

Licence: Public Domain Mark

Credit: Observations on the ventilation of rooms; on the construction of chimneys; and on garden stoves / Principally collected [by R. Willan] from papers left by the late John Whitehurst. Source: Wellcome Collection.

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    [ 26 ] will nece'Tarily he driven down the chimrey A B, carrying along with it both the ftnoke and foot. In order to remedy this inconvenience, the top of the chimney muft he guarded by a pyramidical cap, the faction o! which is represented, fig. 19. The wind then falling upon an inclined furface, wo rld change its direction from b a to d c, and no longer affeCt the rifing columns of fmoke. Such an addition to chimneys, it is prefumed, would occafion no defor- mity, but rather be ornamental to the building. The caps are compofed either of (tone or caft iron: the latter fee ms preferable, as being lefs expenfive, and a better defence to the mortar underneath againft the injuries of the weather. Iron caps, if caft about three tenths of an inch thick, will e .dure for ayes: J O their weight and figure alfo render them not liable to be difturbed by the winds. It is not requifite to make their apertures equal to that of the chimney {haft; but the proportion fhouid be nearly as the fquare of 10 to the hquare- of 14.. This contraction of the aper- ture anfwers two good purposes: it protects the fhaft from rain, and in feme degree defends the rifing column of fmoke from the external cold. The caps need not be let underneath with brick or done-work, but may reft on a little mortar : or /. -4- > , M