[Printed advertisement] Walker's hydraulic phenomenon or universal water elevator / John Walker. 184-. [1 leaf, litho. It also advertises his portable fulcrum and air-proof portable and fixed water closets. Verso bears directions for using the water elevator, and prices of it and the water closets. Walker's manufactory was at 1 Crooked Lane, City, London. Walker took out patents (8,869 of Mar 1841 & 11,669 of Apr 1849) for hydraulic apparatus]