We have just issued an ILLUSTRATED Echelon Diffraction Grating, and we shall be pleased to send a Copy ADAM HILGER, LTD., 75a CAMDEN ROAD, LONDON, N.W. AWARDED GOLD MEDAL ST. LOUIS EXHIBITION, 1904. Telegraphic Address: "SPHERICITY, LONDON." HUXLEY TUBE FURNACE. For use with Criffin's Radial Burner. This furnace has been designed more especially for the combustion of carbon in iron and steel analyses, but it is quite suitable for ordinary organic work. The furnace is so constructed that four com= bustions may be done at one time. The tubes are enclosed in Furnace complete with Burner, Chimney £3 12 Write for Descriptive Circular. JOHN J. GRIFFIN & SONS, LTD., AWARDED MEDALS WHEREVER EXHIBITED, including 9 at the great Paris Exposition of 1900. JAS. J. HICKS, 8, 9 & 10 HATTON GARDEN, LONDON, SCIENTIFIC INSTRUMENT MAKER TO THE WAR OFFICE, INDIA OFFICE, ADMIRALTY, &c. 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The "INCANDANODE" TUBE (so called because it works all day with the Anode RED HOT). This Tube ran from 9 a.m. to 6 p.m. for five days at the Leicester meeting of the B. M. A. last July. The Anode was incandescent the whole time, but the Vacuum was fully maintained. One Tube will last for years. The Vacuum is easily adjustable. THE BELOT SHIELD FOR X-RAY WORKERS. MR. HALL EDWARDS (at the Leicester meeting of the B. M. A. last July) said of this shield: "It is a scientific instrument designed on scientific lines, and overcomes all the objections which exist in the shields previously brought to my notice." THE MEDICAL SUPPLY ASSOCIATION. 228 GRAY'S INN ROAD, LONDON, W.C. Descriptive Circulars (with expert testimony) on application. The "NEW RAPID" MERCURY INTERRUPTER. A break comprising all the latest improvements with a simple and reliable method of raising and lowering the mercury. Fitted with first-class motor of any voltage up to 250. Requires only 2 lbs. of mercury, and is simplicity itself for cleaning. £5 5:0 The "CALDWELL" ELECTROLYTIC INTERRUPTER. Will work on direct or alternating circuits from 50-250 volts without interposing any resistance. Current adjusted by rack and pinion movement, giving perfect regulation with any tube. No expensive platinum parts to replace. Price £3 10 : 0 For larger sizes of above and full particulars of WATSON'S TELESCOPES 9 10 0 Telephone: 10547 Central. WATSON'S MICROSCOPES. 23 DIFFERENT MODELS to select from, suited for every class of research. From £2 : 2 6 upwards. Watson's Microscopes are designed to afford the utmost convenience and comfort combined with absolute accuracy for scientific work. They are up-to-date and of highest quality. For full particulars see WATSON'S 1906 CATALOGUE OF MICROSCOPES (188 pages) post free on application. Send for List No. 6, post free on application. W. WATSON & SONS, Opticians to H.M. Government, 313 HIGH HOLBORN, LONDON, W.C. BRANCHES-16 FORREST ROAD, EDINBURGH, and 2 EASY ROW, BIRMINGHAM. (Established 1837) THE NEW NATURALISTS' CAMERA. Reflex Focussing for Ordinary or Telephoto. Lenses. ILLUSTRATED PROSPECTUS FREE. DALLMEYER L J. H. DALLMEYER, Ltd., 25 Newman St., LONDON, W. MAKERS OF THE CELEBRATED DALLMEYER LENSES. Printed by RICHARD CLAY AND SONS, LIMITED, at 7 && bread Street Hill, Queen Victoria Street, in the City of London, and published by MACMILLAN NATURE A WEEKLY ILLUSTRATED JOURNAL OF SCIENCE Of Nature trusts the mind which builds for aye."-WORDSWORTH. INDEX NUMBER. Illustrated Price List and full particulars post free on application to JOHN J. GRIFFIN & SONS, Ltd. NEGRETTI & ZAMBRA, 38 HOLBORN VIADUCT. KINGSWAY, Branches: 45 CORNHILL, and 122 REGENT STREET, |