292 Of securing houses and their inhabitants from fire, 
2. Another means, then, of preventing the progress of fire in a 
building, is to render it difficult for the fire to make an open passage 
through the combustible substances which it attacks, merely by hav- 
ing those substances closely lined behind with some material which re- 
sists fire. By an attention to this simple rule, Lord Mahon (now 
Earl Stanhope) and Mr. David Hartley, (the person who signed the 
definitive treaty of peace between this country and Great Britain in 
1783,) were able to cover with combustibles, in a flaming state, the 
floors of whole rooms and whole stair-cases, without injury to the 
buildings of which those rooms and stair-cases made a part; neither 
flame nor air being able to pass in this case through and beyond the 
substance of the wood-work on which those burning materials rested. 
—Lord Mahon succeeded in his object on this occasion, by placing 
mortar close below or behind his wood-work ; and Mr. Hartley, if I 
remember well, accomplished his purpose by fixing sheets of iron in 
the same situations, closely connecting these sheets with each other. 
Experiments were publicly exhibited, with perfect success, on each 
of these plans, before numerous spectators of every rank; and if 
my memory does not deceive me, the well known Abbé Mann con- 
firmed the efficacy of this practice by corresponding trials made in 
Flanders.—Here, then, we have a second mode offered to aid our 
attempts to preserve buildings from fire; concerning which mode 
various details, which are truly interesting, will be given in the post- 
script. It shall only be added in this place, that the principle of this _ 
new rule strongly operates, (as has been hinted above,) in favor of 
those wooden ceilings, in France, where the floors above them are 
composed of incombustible materials. 
We now proceed to a third expedient of importance on these ocea- 
sions, of a nature wholly distinct from any thing which has yet been 
mentioned. 
3. Another particular, then, deserving attention as a guard against 
conflagrations, especially where an elevated building i is concerned, is 
the establishment ‘of cisterns for holding water in different parts of 
such edifices; which cisterns may receive their water, either from 
rain, or from any other convenient mode of supply. 
This plan, in effect, was formerly proposed for one of the public 
theatres in London ; and it has certainly been adopted for one of the 
buildings connected with the powder magazines at Purfleet in Essex, 
in England ; and J am not sure that it has not been employed at the 
Capitol at Washington, since | know that this suggestion was once 
