He had met with several fatal cases of apoplexy which had occurred in the theatres, or a few hours after leaving them, and he had been led, with some success, as he alleged, to investigate the cause.

It appeared to him "that the strong vivid light evolved from the numerous gas-lamps on the stage so powerfully stimulated the brain through the medium of the optic nerves, as to occasion a preternatural determination of blood to the head, capable of producing headache or giddiness: and if the subject should at the time laugh heartily, the additional influx of blood which takes place, may rupture a vessel, the consequence of which will be, from the effusion of blood within the substance of the brain, or on its surface, fatal apoplexy." From inquiries he had made among his professional brethren who had been many years in practice in the Metropolis, it appeared to him that the votaries of the drama were by no means so subject to apoplexy or nervous headache _before_ the adoption of gas-lights.

Some of his medical friends were of opinion that the air of the theatre was very considerably deteriorated by the combustion of gas, and that the consumption of oxygen, and the new products, and the escape of hydrogen, occasioned congestion of the vessels of the head.

He thought it probable that this deterioration of the air might act in conjunction with the vivid light in producing either apoplexy or nervous headache.

He found, moreover, that the actors were subject not only to headache, but also to weakness of sight and attacks of giddiness, from the action of the powerfully vivid light evolved from the combustion of gas; and he noted that the pupils of the eyes of all actors or actresses, who had been two or three years on the stage, were much dilated; though this, he thought, might be attributable to the injurious pigments they employed to heighten their complexions; common rouge containing either red oxide of lead or the sulphuret of mercury, and white paint being often composed of carbonate of lead, all of which were capable of acting detrimentally upon the optic nerve.
The statements of "Chiro-Medicus" may seem somewhat overcharged; yet, after allowance has been made for that exaggerated way of putting the case which seems habitual to "the faculty" when it takes up with a new theory, a sufficient residuum of fact remains to justify many of the doctor's remarks.