A WEEKLY ILLUSTRATED JOURNAL OF SCIENCE. 



' ' To the solid ground 

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



X-RAY "FOCUS" TUBES. 



The " Focus" Tubes made by Nf.wton & Co., in accordance 

 ivith the experiments conducted in the Chemical Laboratory at 

 King's College, are still unequalled for rapidity and definition. 



Price 35s. each. 



The above are suitable for Coils giving 2" spark and over. 



Special "Focus" Tubes, 42s. each. 



The above are suitable for Coils giving from 7" to 10" sparks. 



" The definition given by your focus tubes is excellent." — Prof. Oliver 

 f. Lodge, University Cottegf, Liverpool, 



'* Your focusing lube has worked very well, and .is soon as you have 

 mother similar one that you can spare me I shall be glad to have it." — 

 Prof. A. Schuster, The Owens College, IManctiester, 



" We have got excellent results with the focus tubes."— Prof. W. 

 Heato.v, University College, Nottinghavt. 



** The focus lube you sent gives remarkably sharp shadows." — Prof. A. 

 5. Butler, The Universityy St. Andreivs, N.B. 



"I have tried a very large number of v.icuum tubes sold by different 

 nakers for the purpose of giving the X-rays, and find your ' focus tubes ' to 

 )e far and away superior to anything as yet in the market." — Prof. W. F. 

 Barrett, Royal College 0/ Science, Dublin. 



" Les risultais sont merveilleux. "— Dr. Henri van Heueck, Jardin 

 Bctaniquc d.lnvers. 



Sole M.vkers : 



BT xs ^vt7"r o »j sc 00. 



3 FLEET STREET, LONDON. 

 Helium and Argon Spectrum Tubes Norn Ready, \os. 6d. each. 



JOHN J. GRIFFIN & SONS, 12 



22 GARRICK STREET, LONDON, W.C. 



X- ^^^ 



RAYS. 



K RAY TUBES, "FOCUS" Pattern, 27/6 each. 



i96.^" The Special Vacuum Tube 

 .ested in my l.iboratory with very 



Mk. a. a. C. SWINTOX, April i5, I 

 ,'ou recently supplied to me has been 

 iatisfactory results." 



Prof. CHATTOCK, Univ 

 IS was an excellent one-we 1 

 ■oon as you are able." 



INDUCTION COILS. 



3-in., £9; 4in., £12; s-'m.. £15; 6-in., £18. 

 Our own Manufacture, as supplied to " The Lancet," 



Shelford Bidwell, Esq., M.A., F.R.S., and others. 



Mr. ARNOI.HH. ULLYETT, F.R.G.S., &c.—" The C.il gives exceed. 



ngly good results, and with its use I have taken some splendid, well-defined 



hadow photographs." 



Mr. 0. WATMOUGH WEBSTER, F.C.S., F.R.P.S.— 'The Coil is an 



xccllent one, well made, and giving fully the reputed size of spark." 



NALDER BROS, & CO., london 

 D'ARSONVAL GALVANOMETER 



Delivered Free anywhere in U.S.A. for s32 C.O.D. 



■Write for 

 CATALOGUES. 



D'ARSONVAL 

 GALVANOMETER 



(As illuvunted). 



VEEY PORTABLE. 



ENSITIVE. 



N STOCK. 



£5J) 



fc NO AGENTS 



NEGRETTI & ZAMBRA, 



SOLE MAKERS OF 



JORDAN'S (PATENT) SUNSHINE RECORDER. 



Now Simplified Model, 

 adjustable for any 

 latitude, and tho- 

 roughly efBcient. 

 Price £1 7s. 6d. 



Sensitised Charts, 

 Ss. per 100. 



NEGRETTI 

 ZAMBRA, 



Scientific Instrument 

 Makers to the Queen, 



-^ 38 HOLBORN VIADUCT. 



Branches — 45 Cornhill, 

 122 Rkgent Street, 

 London. 



ILLUSTRATED DESCRIPTION POST FREE. 



Telephone No. 6583. Telesrapliic Address, " Negretli, London." 



