The dictum of _Rolle_ that usefulness shall dispense with noisomness has, however, been broken in upon by many more modern decisions; in _Morley_ v. _Pragnel, Cro. Car._ 510, an innkeeper brought an action against the defendant for erecting a tallow-furnace so near his inn that many of his guests left the house, and he recovered damages for the injury; _Tohayle’s_ case was then quoted; he had erected a tallow-furnace in the Strand, which, on indictment, was ordered to be abated, (see also 1 _Hawk. P. C._ 463 where _Rolle’s_ doctrine is questioned.) As to the physical effect of each particular species of bad smell, there may always be some doubt, and much contrariety of evidence is to be expected; this however is certain, that those stenches which may be innocuous to persons in full health, are by no means so to invalids or persons of irritable nerves or stomachs; and to pregnant women they are generally allowed to be dangerous.[553] Habit has also a powerful operation in diminishing the deleterious effects of such effluvia; instances daily occur in which the fumes of certain manufactories affect strangers in the most violent degree, while the artisans engaged in the occupations which produce them; or the persons accustomed from their residence to the full force of their influence, scarcely experience any inconvenience; nay, in some cases, they would even seem to derive a degree of benefit from such an atmosphere, and to suffer whenever they quitted it;[554] like the criminal recorded by Sanctorius, who fell sick when taken out of an infected dungeon, and did not recover until he had been returned into the impure air to which he had been so long habituated. We apprehend that the history of the French bastile would furnish the physiologist with some extraordinary illustrations of the power of habit over the functions of the body. We introduce these remarks for the purpose of shewing, that persons immediately engaged in an indictable manufactory, are not only morally, but physically, incompetent to give evidence in proof of the extent of the mischief it may create: in addition to which it must not be forgotten, that in those works in which are carried on the fusion and volatilization of metals, the workmen employed in the interior of the building escape the deleterious fumes which pass up the flues, and spread desolation over the surrounding district. These views will moreover enable us on many occasions to reconcile the conflicting testimony which is so often given on trials of nuisance, without in the least impeaching the veracity or sincerity of the individual witnesses engaged in the contest.