6th. All the six being opened, the first gave a jet of 27 feet in height. _2nd Experiment._--Six standcocks were then put into plugs, on a main 9 inches diameter in Tooley-Street, the extreme distance being 450 yards, with hose and jets as in the first experiment. The water was brought from the head at Battersea by 4250 yards of iron pipes of 20 inches diameter, 1000 yards of 15 inches diameter, 1400 yards of 9 inches diameter. The weather was nearly the same, but the place of experiment was more protected from the wind than in Union-street. 1st. With one standcock open, a jet 60 feet in height was produced, and 107 gallons per minute were delivered. 2nd. The second standcock was then opened, and the difference in the first jet was barely perceptible. 3rd. Other two standcocks being opened, the first jet was reduced to 45 feet in height, and the delivery to 92 gallons per minute. 4th. All the six standcocks being opened, the first jet was further reduced to 40 feet high, and the delivery to 76 gallons per minute. _3rd Experiment._--Two standcocks, with hose, &c., as in the first experiment, were then put into a service-pipe, 4 inches diameter and 200 yards long, in Tooley-street, the service-pipe was connected with 200 yards of main 5 inches diameter, branching from the main of 9 inches diameter. The weather was still the same as at first, but the wind did not appear to affect the jets, owing to the buildings all round being so much higher than the jet. 1st. The standcock nearest the larger main was opened, and a jet of 40 feet high was produced, delivering 82 gallons per minute. 2nd. Both standcocks being opened, the first gave a jet of 31 feet, and delivered 68 gallons per minute. 3rd. The standcock farthest from the large main only being opened, gave a jet of 34 feet, and delivered 74 gallons per minute. 4th. Both standcocks being opened, the farthest one gave a jet of 23 feet, and delivered 58 gallons per minute. When both these plugs were allowed to flow freely without hose, the water from that nearest the large main, rose about 18 inches, and the farther one about 1 inch above the plug-box. [Illustration: FIG. 7. Common Fire-plug.] These and other experiments prove the necessity of placing the plugs on the mains, and not on the service pipes, where there are mains in the street. The different modes of obtaining water from the mains or pipes are shown in the accompanying drawings. (Fig. 7) is a section of a common plug when not in use. [Illustration: FIG. 8. Fire-plug with canvas cistern.]