A few words must be said with respect to the peculiar construction of the engines. In the first place the parts are so arranged that no steam whatever escapes into the tunnel. This is accomplished by having a large tank on each side of the engine. These tanks together contain about 1,000 gallons of water. The exhaust steam is turned into them, instead of through the funnel in the ordinary way. The second peculiarity of the engines is that they are constructed with large heating surface. The steam is raised to a pressure of about 130 lbs. at starting, and by the time the journey through each tunnel, between station and station, is performed, it has been reduced to about 80. The damper is kept on during the entire journey. It will thus be seen that the combustion of fuel in each tunnel must be very small indeed, the fire being simply kept in, without any draft through the fire box. Recently, the directors of the company, with the view to satisfying public feeling in every possible way, forwarded to the Vestries of St. Marylebone and St. Pancras, applications for permission to effect openings to the external air at several points of the Marylebone and Euston Roads—where important roads cross this thoroughfare—by means of handsome and ornamental hollow columns, which should be connected with the railway, and would support street lamps similar to those now placed at frequented crossings in various parts of the town. It is a fact beyond all question that, unvaryingly, there are fewer persons belonging to the staff of the Metropolitan Railway, in proportion to their numbers, absent from duty on account of illness, than on other railways. We have seen returns, fully confirming the statement to this effect. We believe they were published by Mr. Myles Fenton, in the newspapers a few months ago. During the year ending the 30th of June, 1867, the enormous number of 22,458,067 passengers[142] were conveyed by the Metropolitan Railway Company without accident, injury, or (as far as the world knows) ill effects to any one of them.