A WEEKLY ILLUSTRATED JOURNAL OF SCIENCE 



" 7t7 thi solid gratmd 

 0/ Nature trusts the mind which builds for aye''' — WoRDSWORTH 



No. 473, Vol. 19] THURSDAY, NOVEMBER 21, 1878 



[Price Sixpence 



Registered as a Newspaper at the General Post Office.] 



[All Rights are Reserved. 



BROWNING'S ELECTRIC REGULATORS. 



Fig. I. Fig. 2. Fig. 3. 



Small ELECTRIC REGULATOR wth Parabalic Reflector (Fig. i). This Regulator -will give a pDwerful and steady light, with from 10 to 20 



quart-size Grove's or Bunsea's Cells. Price ... ... ... ... ... ... ... •• ... ... ... ... ... £2 5 



Small ELECTRIC REGULATOR, without Reflector (Fig. 2), for use in the Lantern, with adjustment for keeping the points of the burning 

 carbons at one height, or separating them to any required distance. This adjustment is indispensable for projecting the Spectra of Burning 

 Metals on a Screen. With 20 quart-size Bunsen's Cells, this Regulator will illuminate a lo-feet disc Price ... ... ... ... 2 1.5 



Parabolic Reflector, if required, extra ... ... ... ... ... ... ... ... ... ... ... ... — 6 6 



Medium Size AUTOM.A.TIC ELECTRIC REGULATOR. This Lamp works well with from 20 to 30 pint Grove's Cells, or the same number 



• of quart Bunsen's (as Fig. 3). Price ... ... ... ... ^. ... ... ... ... ... ... .^ 7 10 



Parabolic Reflector, extra ... ... ... ... ... ... ... .„ ... ... ... .„ ... ... 1 15 



Large Size AUTOMATIC REGULATOR. From as to 50 quart Grove's Cells, or the same number o£ a quart Bunsen's, should be used with 



this Lamp (Fig. 3). Price ... ... ^ ... ... ... ... ... ... ... ... ... ... —990 



Parabolic Reflector ... ... ... ... ... ... ... ... ... ... ... .». ... „. ... 2 2 



In these Regulators both carbons are moved by the electricity of the battery employed (without the aid of clockwork) ; the light remains uniform 

 in height and more steady in action than any of the expensive regulators previously introduced. 



Illustrated Catalogue and Description of Si-ectroscopks sent for 7 Stamps. 



JOHN BROWNING, 



OPTICAL AND PHYSICAL INSTRUMENT MAKER TO H.M. GOVERNMENT, THE ROYAL SOCIETY, THE 

 ROYAL OBSERVATORY OF GREENWICH, AND THE OBSERVATORIES OF KEW, CAMBRIDGE, 

 MELBOURNE, THE U.S. NAVAL OBSERVATORY, CAMBRIDGE AND HARVARD 

 I UNIVERSITIES, HOBOKEN COLLEGE, &c., &c. 



63, STRAND, ^W.C. 



FACTORY—SOUTHAMPTON STREET, LONDON, W.C. ESTABLISHED 100 YEARS. 



