"The Wheel of Fortune" traces astrological knowledge in ancient Greek manuscripts from Baghdad's founder, Caliph Al-Mansur, via the Muslim monastery/medical school at Gundeshapur, to the medieval Church's need for alarm clocks (the water horologium and the verge and foliot clock). The clock mainspring gave way to the pendulum clock, but the latter could not be used by mariners, thus the need for precision machining by way of Huntsman's improved steel (1797) and Maudslay's use (1800) of Ramsden's idea of using a screw to better measure (which he took from the turner's trade). This process made a better mainspring and was also used by the Royal Navy to make better blocks. Le Blanc mentioned this same basic idea to Thomas Jefferson, who transmitted this "American system of manufactures" – precision machine-tooling of musket parts for interchangeability – to New Englanders Eli Whitney, John Hall, and Simeon North. The American efficiency expert Frank Gilbreth and his psychologist wife later improved the whole new system of the modern production line.