PHILOSOPHICAL TRANSACTIONS 
OF THE 
ROYAL SOCIETY OP LONDON. 
Series A, Yol. 217. Pp. 361-410. 
[Plates 4-18.] 
A CRITICAL STUDY OF SPECTRAL SERIES. 
Part IV.—THE STRUCTURE OP SPARK SPECTRA. 
BY 
W. M. HICKS, F.R.S. 
LONDON: 
PUBLISHED BY THE ROYAL SOCIETY, 
AND SOLD BY HARRISON AND SONS, ST. MARTIN’S LANE, W.C., 
Printer s' tn ©rtrtnarg tn iHajestn. 
1917. 
A 558. 
23.10.17 
Price Three Shillings and Sixpence. 
