May 25, 1905] 



MA TURE 



At the 



OPTICAL 

 CONVENTION, 



May 31 to June 3 



(At the Northampton Institute, 

 Clerkenwell, London, E.G.), 



a number of Optical and other 



Physical Instruments will be 



exhibited by 



THE CAMBRIDGE SCIENTIFIC 

 INSTRUMENT CO., LTD., 



CAMBRIDGE, ENGLAND. 



TODE 

 HARK 



BRAND 



jTABLOlD'i 



1 PnOTOGCAPAIC 

 CAEniCALS 



NO WEIGHING 

 NO MEASURING 

 NO WASTE 



ALWAYS READY 

 ALWAYS ACCURATE 

 ALWAYS RELIABLE 



timOY INANY DARK ROOM 

 ABSOUTELY INDlSPENSAnii 

 TO TOURISTS 



Ssid br »» Ch«miiM 



Burroughs WELLCone & Co. 



SNOW HILL BUILDINGS, LONDON. 



This Illustration represents the NATURE OF SPARK produced by the 



NEW HIGH POTENTIAL APPARATUS, 



which also yields ALTERNATING CURRENTS OF BOTrl HIGH AND LOW POTENTIAL. 



?^- The apparatus is «<>"■ "" '■'<■"■ here, or Illustrated Descriptive Pamphlet may be had post free upon application. 



IS£:N^THiLI^ &, CO., 85 Mortimer Street, London, W. 



Cantraciars to the Admiralty, War, India, and Colonial Offices. Cic. 



