Letter, from Henry Oldenburg to John Cruzado, dated at London Transcribes Flamsteed's reply to Cruzado's letter concerning the prime meridian, the equation of time, the investigation of longitude, about a small instrument to aid observations with the accuracy of two or three minutes; that Jonas Moore had become a patron of astronomy and so possibly an observatory would be built. Table attached with 'equations of apparent time (as mentioned above) the Earth's aphelion being in the seventh degree of Capricorn, which may serve throughout this century, interpolating the sun's true place'. 3 February 1676