

A WEKKI.Y ILLUSIKAIKJJ JOURNAL OF SCIKNCK. 



" To the soliil ground 

 0/ Nature trusts the mind which builds for aye." — WoKUSWOKTH. 



OPTICAL PROJECTION. 



EXPERIMENTS 



ON 



LIGHT. 



(See 



Illustrated Catalogue, 



Six Stamps. ) 



... KSLIUE, f(ir showint^ the motion of Lit;hl, .Vc, 15s. 



UlUTl-: IJGHT-.SLIUt;, for .showing the com|iosition of 



White Light on the Screen, 12s. 6d. 



IV E A7V T o av «SC CO., 



3 FLEET STREET, LONDON. 



NEW 



MICROSCOPE 



Tin: 



"BRITISH STUDENTS." 



Microscope Stand No. 66, as 

 figured, with Iris Olaphragm, 

 One Bye-piece; Double Nose- 

 piece. Ttwo Object-glasses, 2/3" 

 and 1/6", adjusted to be In 

 about focuB, and the whole 

 packed In polished Mahogany 

 Case, 



£6:8:6 



R. & J. BECK, Ltd. 



68 CORNHILL, LONDON, E.G. 



BROWNING'S PLATYSCOPIC LENS. 



With LarKcr AnKle.s, Incrcfised Field, .ind Improvtd Definition 



AN ACHROMATIC COMBINATION, 



COMBINING TIIIC DKI'INITION OV A MICKO.SCOril WITH THB 

 I'ORTAItlLITV OP A I'OCKET I.BNS. 

 " If you carry a small Platyscopic Pocket Ivcnt* (which every observer of 

 Nature oiiKlii to ilo)."-f;iiANT Ai.i.RN in Knmuledge. 



Tin Pl.in .r .r|,;, I..r, , i inv:.lu.iblc lo holanists, mineraluKi«ls, or enlo- 

 tnul'i;! t .1 ji I ,. I, . ..i..iii three limes as far from the object aft the 

 C'j<l(iiii:.i..ii I r II , [111 .illiiws opa(|ue objects to be examineu easily. 



TTi'- I'l.iry I r.jii. I.i II I iii.'kIc of four degrees of power, masnifyinK 

 respectively lo, 15, vo, and 30 diams. ; the lowest power, having the largest 

 field, is the best adapted for general use. 



The Lenses are set in Kbonite Cells, and mounted in Tortoiseshell Frames. 



/'/■/Vc oflhc /•litlvuii/ih /..-IIS, innnnlril in Torlitiseilirll, magnifyiu): tilhtr 



,,:. 1.^1 ao ,„.-,.,,//V/,//,./,->-i, ,.„,/, /.o7,.,./., IBs. 



/„ „,; /.;■/, :,;/ <,,,m„,l \ il :; ,.,.,. I, /;.■,,;,, 1 7S. 6d. 



Illu.lr;.!...! II....I ,i,,lii,i, ...u< Ur. . 



JOHN BROWNING, 63 STRAND, LONDON, W.C- 



SPECT AC LES 

 ELECTRIC LICHT, INCANDESCENT GAS. 



AiK.I olliei- Powei-lul 1 1 1 1 1 ii i ] i um l.t,. 



NEGRETTI & ZAMBRA'S 

 THERMOSCOPIC LENSES 



i'rotiu the Kyesfruin Ol.u.r, ;,nd 

 RBNDBR THB LIGHT SOFT AND OOOL. 



Illu.lritlcl Pri(t /.nil «/ O/itUnl and MclctiroluKkal Inslriimenti 

 Irr,: hy l\>U lo all /art^ ,./ Ilic World. 



NEGRETTI AND ZAMBRA, 

 SCIENTIFIC INSTRUMENT MAKERS to THE QUEEN, 



38 HOLBORN VIADUCT, E.G. 



BRANCHES: 46 CORNHILL ; 122 REGENT 87REET. 



