THE 



SCIENTIFIC TEANSACTIONS 



or THE 



ROYAL DUBLIN SOCIETY. 



VOLUME IV. (SERIES II.) 



VIII. 



THE CONSTETTCTION OF TELESCOPIC OBJECT-GLASSES FOR THE INTER- 

 NATIONAL PHOTOGRAPHIC SURVEY OF THE HEAVENS. By SIR 

 HOWARD GRUBB, M.A.I., F.R.S., Hon. Sec, Royal Dublin Society. 



DUBLIN: 



PUBLISHED BY THE ROYAL DUBLIN SOCIETY. 



LONDON: WILLIAMS AND NOEGATB. 



FEINTED AT THE UNIVERSITY PRESS, BY PONSONBY AND WELDRICK, 



PEINTEES TO THE SOCIETY. 



1891. 



