Jang created new significant designs for water clocks, armillary spheres, and sundials. The book on sundials by Mayall & Mayall describes the Universal Capuchin sundial. Clocks, hourglasses, sundials, and other timepieces both call to mind that time is passing. Equation clocks satisfied the demand for clocks that always agreed with sundials. It was measured with sundials and water clocks. Water clocks, along with the sundials, are possibly the oldest time-measuring instruments. Both appear to be sundials with gnomon curves etched on a flat surface. Mechanical clocks kept the mean time, as opposed to the apparent time displayed by sundials. Analemmatic sundials are sometimes designed with a human as the gnomon. On some sundials, the gnomon is vertical. The phrase is a common motto, particularly on sundials and clocks. The wings are terminated by pavilions which feature large sundials set beneath their pediments. Many ornamental sundials are designed to be used at 45 degrees north. This octagonal clocktower showed scholars and shoppers both sundials and mechanical hour indicators. Sundials are sometimes combined into multiple dials.