THE 



SCIENTIFIC PROCEEDINGS 



OF THE 



ROYAL DUBLIN SOCIETY. 



Yol. XVI. (N.S.), lo. 18. MARCH, 1921. 



A DIEECT READING ULTRA-MICROMETER. 



BY 



JOHN J. BOWLING, M.A., M.R.LA., F.Inst.P. 



[A uthors alone are responsible for all opinions expressed in theirCommunicaiions.~} 



> f'Vl CI 'inc.") •J^\ 



DUBLIN 



:^:« ^1 1922 ^1 



PUBLISHED BY THE ROYAL DUBLIN SOCIETY. 

 LEINSTER HOUSIC, DUBLIN. 



WILLIAMS AND NOEGATE, 

 14, HENRIETTA STREET, COVENT GARDEN, LONDON, W.C. 2. 



1921. 



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