A WEEKLY ILLUSTRATED JOURNAL OF SCIENCE 



"To the solid ground 

 Of Nature trusts the mind -which builds for aye." — Wordsworth 



No. 521, Vol. 20] 



THURSDAY, OCTOBER 23, 1879 



[Price Sixpence 



Registered as a Newspaper at the General Post Office.] 



[All Rights are Reserved. 



BROWNING'S ELECTRIC REGULATORS.^ 



Fig. I. 



Fig. 



Fir,. 3. 



This Lamp works well with from 20 to 30 pint Grove's Cells, or the same number 



Small ELECTRIC REGULATOR with Parabolic Reflector (Fig. i). This Regulator will give a powerful and steady light, with from 10 to 20 



quart-Size Grove s or Bun&en's Cells. Price ... ... 



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



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



Metals on a bcreen. With 30 quart-sue Bunsen's Cells, this Regulator will illuminate a lo-fcet disc. Price 

 Parabohc Reflector, if required, extra ... 

 Medium Size AUTOiVIATIC ELECTRIC REGULATOR. 



of quart liunsen's (as Fig. 3). Price ... ... ,„ ... ,„ ,., 



Parabohc Reflector, extra ... ... ... ... ... ... ... ]., [" "* 



Large Size AUTOMATIC REGULATOR. From 25 to 50 quart Grove's Cells, or the same' number'of 2 quart Bunsen's, should be used with 



this I.amp (Fig. 3). Price ... ... ... ... ... ... ... .., 



Parabolic Reflector ... ... ... ... ... ... ... ... ... ... ... ... 



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

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

 Illi/stkated Catalogue of Electric Lamps, Lantiirns, Slides, &c.. Price Sixi'ence 



£2 6 



JOHN BROWNING. 



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



ROYAL OHSERVATORY OF GREENWICH, AND IHE OBSERVATORIES OF KEW, CAMBRIDGE, 



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



UNIVERSITIES, HOBOKKN COLLEGE, &c., &C. 



63, STRAND, ^W.C. 



F.ACTORY-SOUTHAMPTON STREET, LONDON, W.C. 



ESTABLISHED loo YEARS. 



