THE 
SCIENTIFIC PROCEEDINGS 
OF THE 
ROYAL DUBLIN SOCIETY. 
Wol; XT. (N.S.), No. 19, AUGUST, 1907. 
ON SOME DEVICES FACILITATING THE STUDY 
OF SPECTRA, 
BY 
WALTER NOEL HARTLEY, D.Sc., F.R.S. 
ROYAL COLLEGE OF SCIENCE, DUBLIN. 
(PLATE XxX.) 
[Authors alone are responsible for all opinions expressed in their Communications. | 
DiC TE TEN: 
PUBLISHED BY THE ROYAL DUBLIN SOCIETY, 
LEINSTER HOUSE, DUBLIN. 
WILLIAMS AND NORGATE, 
14, HENRIETTA-STREET, COVENT GARDEN, LONDON, W.C. 
Io Oe 
Price Sixpence. 
