Letter from Lewis Fry Richardson, on a paper 'The aerodynamic drag of the earth’s surface and the value of von Karman’s constant in the lower atmosphere' by Percival Albert Sheppard to Alfred Charles Glyn Egerton The paper has obvious merits but the author should respond to criticism of his experimental technique. He makes 'no allusion to the hydrostatic force exerted by the oil on the floating plate'. The experimental situation may require further investigation. [Published in Proceedings of the Royal Society A, 1947]. Endorsed on recto as received 25 February 1946. 22 February 1946