Letter from Thomas Gold to Professor B Y Mills FRS, School of Physics, University of Sydney, Sydney, NSW, Australia Thanking Mills for a letter and noting the benefits of a joint project for radio astronomy. Hopes Mills can visit Cornell and Puerto Rico. The Arecibo antenna is still not in order, but Gordon believes that a small change will put things right. Gold believes that a new feed will have to be designed and made. Asks how Mills's cross is doing and proposes a joint programme of radio sources where the cross and dish overlap. 4 May 1964