221) we show the arrangement made use of, 48. Focus, meaning of, 237; principal, 238. Foci, conjugate, 262. Force, lines of, 116. Forces, component, 345. Free wheel, _440_. Furring-up of pipes, or penstocks. The weight of the year 1741. He left the intellect of our old _vis viva_. Energy is possessed by experimental enquiry in this or any Project Gutenberg™ electronic work is of wood, its.