File:FRONT VIEW OF A BOAT.jpg

English: Drawing by William Alexander, draughtsman of the Macartney Embassy to China in 1793. A canal lock which the Embassy passed on November 6, 1793, during the travel from Han-tcheou-fou to Tchu-san. The drop of water was six foot; the water ended within one foot of the upper edge of the beam over which the flat-bottomed river boat had to be pushed. The lock consisted of a double glacis of sloping masonry, with an inclination of about forty degrees from the horizon. The pushing machinery was represented by two capstans in this particular lock, in other locks, four or six could be used. Alexander noted that canals were used as a preferred means of transportation and communication in the mountainous areas of China. Image taken from The Costume of China, illustrated in forty-eight coloured engravings, published in London in 1805.