We were now introduced to the great engine. What a monster! Imagine an enormous see-saw, with a steam engine at one end, and a pump at the other. Fancy this ‘beam,’ some ten yards long, and twenty-eight tons in weight, moving on a pivot in the middle, the ends of which show a circumference greater than the crown of the biggest hat ever worn. See, with what earnest deliberation the ‘see,’ or engine, pulls up the ‘saw,’ or balance-box of the pump, which then comes down upon the water-trap with the ferocious _àplomb_ of 49 tons, sending 400 gallons of water in one tremendous squirt nearly the twentieth part of a mile high;—that is to the top of the stand-pipe. ‘We have a smaller engine which “does” 150 gallons per stroke,’ remarked our informant: ‘each performs 11 strokes, and forces up 4400 gallons of water per minute, and thus our average delivery per diem throughout the year is from 4,000,000, to 5,000,000 gallons.’ ‘What proportion of London do you supply?’ asked Mr. Lyttleton. ‘The quadrangle included between Oxford Street, Wardour Street, Pall-Mall, and Hyde Park; besides the whole of Notting-hill, Bayswater, and Paddington. We serve 14,058 houses, to each of which we supply 225 gallons per day, or, taking the average number of persons per house at nine, 25 gallons a head; besides public services, such as baths, watering streets, or manufactories; making our total daily delivery at the rate of 252 gallons per house. This delivery is performed through 80 miles of service pipes, whose diameter varies from 3 to 30 inches. ‘Now,’ said my companion, sharpening his pencil, ‘to go into the question of supply.’ He then unfolded his pocket soufflet, and brought out a calculation, of quantities derived, he said, from parliamentary returns and other authorities more or less reliable:—