Replying to the Coroner, Professor Rodgers said he did not think the deficiency of oxygen would act injuriously upon a delicate person passing through the tunnels; and he considered that the amount of carbonic and sulphurous gases in the tunnels could not have been injurious to the woman. There was not a sufficient accumulation of these gases to be of injury to the public health. The woman had eaten heartily, was laced tightly, and had a diseased heart; he, therefore, did not think the deficiency of oxygen could have hastened her death.
The joint report of Drs. Bachhoffner, Letheby, and Whitmore was then read and put in evidence. It stated that the analysers collected samples of the air on three separate occasions:—First, immediately after the trains had ceased running at night; second, just before they commenced running in the morning; and third, in the afternoon, between four and five o’clock, a period of the day when there was generally the largest amount of traffic. The samples, twenty-eight in number, were analysed for sulphurous acid, carbonic acid, carbonic oxide, coal gas, and oxygen. The presence of sulphurous acid having been sought by the most delicate chemical test—namely, its action upon iodic acid and starch, which was capable of showing the presence of one part by volume of sulphurous acid in 100,000 parts of air, but by such test the presence of that acid could not be detected; and from this the analysers concluded that its volume was less than the above in the tunnels. The mean proportion of carbonic acid was about 6 in each volume of 10,000. The amounts of coal-gas and of carbonic oxide were so small as to be barely discoverable. The amount of oxygen in the tunnels and stations was not in any case deficient. These results proved that in no instance was the air found to be vitiated to any material extent, although the air taken in the afternoon was less pure than that taken at night. The presence of sulphurous acid gas in the tunnels and stations, which at times was appreciable to both taste and smell, must not be taken as an indication that this gas existed in dangerous quantities, for as little as one part of this gas in 100,000 parts of atmospheric air was strongly perceptible both to taste and smell. The partial combustion of the wood forming the breaks, when acting upon the tires of the wheels, also produces a pungent smell. The analysers were of opinion that, having regard to the cubical volume of the trains, the short time occupied by them in passing through the tunnels and stations, the large volume of air they displaced, and the increased impetus given to the horizontal movements of the air by the rapidity of their transit, the vitiation of the atmosphere could not be of a serious character, and this accorded with the results of their analysis. The tunnels were dry and free from infiltration of liquid or other matters prejudicial to health. The general health of the _employés_ of the company was such as to afford unquestionable proof of the sanitary condition of the air in the tunnels. The report ends thus:—“From the foregoing facts, we are enabled confidently to state that the atmosphere of the Metropolitan Railway is not unwholesome or injurious to health.”