A WEEKLY ILLUSTRATED JOURNAL OF SCIENCE 



" To the solid ground 

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



No. 497, Vol. 20] 



THURSDAY, MAY 8, 1879 



[Price Sixpence 



Registered as a Newspaper at the General Post O/Hce.] 





[All Rights are Reserved. 



BROWNINGS 



ASTRONOMICAL 

 TELESCOPES 



Silvered Glass REFLECTING TELE- 



,-j ., -_ SCOPE, with Parabolic Mirror 6i in. 



T^.^iS' diameter, 5i ft. focus, mounted on Altazi- 



j^'.^'Sp*- muth Stand, with quick and slow fine 



..„j^_,..v*.3*if^t screw motions, both in altitude and azi- 



i-U-'lif - <0 '«* tl^* ranih., and two Hook's joints, and three 



';,,' V*iYZ«fit?^ eye-pieces magnifying respectively loo, 



J>rr^Vr?'^^ Ta^' -°°> 3"<^ 300 diameters. Powers up to 



rS^«fli^-^'^^^^^X 450 diameters may be used on this instru- 



ment with advantage. 



PRICE £36 6s. Od. 



LIST OF PRICES OF TELESCOPES FREE. 



Sixth Edition, with much New Matter. 

 A PLEA for REFLECTORS : 



Being a Description of the New Astro- 

 nomical Telescopes, with silvered glass 

 specula, and instructions for using and 

 adjusting them, with many Illustrations 

 and Coloured Frontispiece of Jupiter 

 By JOHN BROWNING, F.R.A.S.— 

 One Shilling, post free. 



JOHN BROWNING, 



optical and Physical Instrument Maker to 

 H.M. Government, the Royal Society, the 

 Royal Observatory of Greenwich, and the 

 Observatories of Kao, Cambridge, Melbourne, 

 the U.S. Naval Observatory, Cambridge and 

 Harvard Universities, Hoboken Collejre. 



63, STRAND, W.C, LONDON. 



Factory — Southamptan Street and Exeter Street, 

 LoodoD. 



Plll» MiDAL, 1861. EsTABLISHtD tOO VXAItS. 



Microsctpes, Spectroscopes, Opera Classes, 



