Clench_, in the year 1692, may be adduced as an example; this gentleman was strangled in a hackney coach by two men, while driving about the streets of the city, without the coachman having the slightest knowledge of the transaction, until he afterwards found him quite dead, kneeling down with his head on the seat, and a handkerchief bound about his neck, in which was a piece of coal, placed just over the windpipe.[46] 4. BY SMOTHERING. In this act the transit of the air into the lungs is prevented by forcibly closing the nostrils and mouth. It is very obvious that such a mode of destruction can very rarely occur in an adult; for a comparatively feeble resistance will be sufficient to overcome the assailant in such an attempt. It may, however, occur accidentally; it is not difficult to imagine that a person, in a fit of intoxication, may be unable to extricate himself from a position in which he might fall, and in which respiration could not be performed. In children this mode of suffocation is less rare, and it may be either the result of design or accident, to which we shall have occasion to refer, when treating the subject of Infanticide. 5. BY THE INHALATION OF AIR DEPRIVED OF OXYGEN. There are many gases, the inspiration of which occasions death; some of these act simply by excluding oxygen, while others exert an absolutely deleterious action in consequence of the specific powers which they possess. It is exclusively to the first species that our attention is at present to be directed; the latter will constitute matter for future consideration, under the title of _Aërial Poisons_. It is a fact too well established to require any discussion, that _oxygen_ is the only principle which is capable of producing the necessary changes in the blood, during its transmission through the lungs; and that, accordingly, whenever atmospheric air is deprived of this principle, it is no longer capable of supporting life, and the animal immersed in it instantly dies. It is thus that death takes place from exposure to the fumes of charcoal[47], to those of lime-kilns, to the atmosphere of cellars, caverns, wells, and dungeons.[48] The asphyxia from privies, drains, and common sewers, depends upon a different cause, and will be considered under the head of _Sulphuretted Hydrogen_, in the history of poisons.