PROCEEDINGS 
OF THE 
ROYAL SOCIETY OF EDINBURGH. 
SESSION 1913-14. 
Part III.] VOL. XXXIV. [PP- 209-371. 
CONTENTS. . 
NO. ' PAGE 
XVI Some Factorable Continuants. By W. H. Metzler, Ph.D., . 223 
{Issued separately September 3, 1914.) 
XVII. The Analytical Study of the Mechanism of Writing. By 
James Drever, M.A., B.Sc. Communicated by Dr 
Alexander Morgan, ..... 230 
(. Issued separately September 3, 1914.) 
XVIII. Abnormal Echinoids in the Collection of the Royal Scottish 
Museum. By James Ritchie, M.A., D.Sc., Royal Scottish 
Museum; and James A. Todd, M.A., B.Sc. Communi- 
cated by William Eagle Clarke. (With a Plate), . 241 
{Issued separately September 4, 1914.) 
XIX. Description of a Projection-Model of the 600-Cell in Space 
of Four Dimensions. By D. M. Y. Sommerville, M.A., 
D.Sc., Lecturer in Mathematics, University of St Andrews. 
(With a Plate), ...... 253 
{Issued separately September 29, 1914.) 
XX. Changes of Electrical Resistance accompanying Longitudinal 
and Transverse Magnetizations in Iron and Steel. By 
Professor C. G. Knott, D.Sc., .... 259 
{Issued separately December 14, 1914.) 
[' Continued on page iv of Cover . 
EDINBURGH : 
Published by ROBERT GRANT & SON, 107 Princes Street, and 
WILLIAMS & NORGATE, 14 Henrietta Street, Covent Garden, London. 
MDCCCCXIY. 
Price Six Shillings and Sixpence. 
