A WEEKLY ILLUSTRATED JOURNAL OF SCIENCE. 



' ' To the solid ground 

 Of Nature trusts the miiul which builds for aye." 



-Wordsworth. 



X-RAY "FOCUS" TUBES. \ BROWNING'S SPECTROSCOPES. 



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

 with the experiments conducted in the Chemical Laboratory at 

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



Price 30s. 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 exxellent." — Prof. Oliver 

 J. LoDtiE, University Cifltege, Liverpool. 



" Your focusing tube has worked very well, and as soon as you have 

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

 Prof. A. Schuster, TAr Owens College, Manchester. 



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

 Heaton, University College. Nottinghatn. 



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

 S. Bltlek, The University, St. Andreivs, N.J3. 



**A .have tried a very large number of vacuum tubes sold by different 

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

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

 Barrett, Royal College of Science, Dublin. 



" Les r^svltats sont mer\-eilleu.\." — Dr. Henri \an Heukck, Ja}din 

 Botanique d'.Anvers. 



Sole M.akeks : 



»r IS 'w T o »ar ^B CO. 



3 FLEET STREET, LONDON. 



The Student's Spectroscope has a prism of extremely dense glass, of very 

 superior workmanship ; the circle is divided, and reads with a vernier to 

 single minutes ; the slit is furnished with a reflecting prism, by means of 

 which two spectra can be .shown in the field of view at the same time. The 

 instrument will divide the D line in the Solar Spectrum, or the yellow Sodium 

 lines distinctly. With a slight alteration of the adjustments, the instrument 

 can be used for taking the refractive and di.spersive powers of solids or 

 liiiuids. The Student's Spectroscope is the best instrument for the Labora- 

 tory and for all general work in Spectrum Analysis. 



PRICE, COMPLETE IN CABINET, £6 lOs. Od, 



Ilhistrate.i Catalogue of Spectroscopes, post free. 



Helium and Argon Spectrum Tubes Now Ready, loj-. (,d. each. JOHN BROWNING, 63 STRAND, LONDON, W.C. 



No Sclentiflc Man NEGRETTI & ZAMBRA, 



should 

 be without a 



FRENA 



CAMERA. 



SOLE MAKERS OF 



Fu// particulars 



free 

 on application. 



R.&J.BECK,M, 68Gornliimon(lon,E.C. 



JORDAN'S (PATENT) SUNSHINE RECORDER. 



New Simplified Model, 

 adjustable for any 

 latitude, and tho- 

 roughly efficient. 



'Price £1 7s. 6d. 



Sensitised Charts, 



5s. per 100. 



NEGRETTI 

 ZAKIBRA, 



Scientific Instrument 

 Makers to the Queen, 



38 HOLBORN VIADUCT. 

 Branches— 45 Cornhill, 

 122 Regent Street, 

 London. 



ILLUSTRATED DESCRIPTION POST FREE. 



Telephone No. 6=83. Ttlegraphic .\ddress, " Negretti, London." 



