Letter from Dr A C Strickland, Executive Editor, Space Research XI, COSPAR, The Royal Society, 6 Carlton House Terrace, London SW1, England In reply to the letter of 17 June, Figure 2 of Professor Gold's paper was taken from a book entitled 'Geology illustrated' byJohn S Skelton. This figure does need an acknowledgment and we are in the process of obtaining permission for its use. This will be sent on as soon as it is received'.. 13 July 1970