PHILOSOPHICAL TRANSACTIONS 
OF THE 
ROYAL SOCIETY OE LONDON. 
Series A, Vol. 221. Pp. 29-71. 
ON A THEORY OF THE 
SECOND ORDER LONGITUDINAL SPHERICAL ABERRATION 
FOR A SYMMETRICAL OPTICAL SYSTEM. 
BY 
T. Y. BAKER, B.A., 
INSTRUCTOR COMMANDER, R.N., 
AND 
L. N. G. FILON, M.A., D.Sc., F.R.S. 
GOLDSMID PROFESSOR OF APPLIED MATHEMATICS AND MECHANICS IN THE UNIVERSITY OF 
LONDON. 
Printed and Published for the ROYAL SOCIETY by 
HARRISON AND SONS, 44-47, ST. MARTIN’S LANE, LONDON, W.C. 2, 
printcrg in Or&tuarg to gig iHajes'tjj. 
1920. 
Price Three Shillings and Sixpence. 
A 583. 
16.6.20 
