sewers. "Sewers and house drains were constructed on no scientific principle.[3] The walls were rough, irregular and porous. Naturally deposits took place in them; hand cleaning was considered a normal incident to the history of the sewer, and irrespective of the volume of sewage to be conveyed, sewers were made large enough to admit the passage of a man to facilitate cleaning." In 1852, the General Board of Health under the Public Health Act, made their first report to the British Parliament, and advocated very strongly the introduction of smaller pipes in lieu of the large brick and stone drains then in use for house drainage. Prior to this date, the first report of the Metropolitan Sanitary Commission, London, appeared, which, while not to be taken as advocating exclusively the use of small pipes, yet pointed out the necessity of reducing the dimensions and altering the shapes of the old stone and brick structures. From this period, then, can be assumed the adoption and first use of earthenware pipes for house drains and public sewers. The construction of sewers in Paris dates from 1663, but the earliest of those still in use are not earlier than the beginning of this century. Before the great epidemic of cholera in 1832, the total length of sewers was not more than 21 miles. The sewers of Paris to-day aggregate over 750 miles in length, and constitute one of the sights of the city. According to Mason,[4] "They may be inspected without charge on the first and third Wednesdays of each month in summer, by writing for a permit to the Prefect de la Seine. Descent is commonly made near the Madeleine by a substantial stairway of stone, and the boats awaiting the party at the foot of the steps are fully as large and quite as comfortable as Venetian gondolas. The great sewer, which is tunnel-like in dimensions, being 16 feet high and 18 feet broad, is, on occasions of a visit, lighted with lamps alternately red and blue, and as these stretch away into the distance the effect is decidedly striking. Under ordinary circumstances, the sewage confines itself to the center channel, but upon occasions rises above the sidewalk on either hand. The central channel is about 10 feet wide and 4 feet deep with a curved bottom, and a walk on either side. The boats with their loads of visitors are pulled by ropes in the hands of attendants who walk along the sidewalks. On either side of the sewer may be seen the large mains, carrying the city water supply, also the telegraph cables."