KNOWLEDGE. 



February, 1915. 



"B.J. ALMANAC 1915," The big book of photo- 

 graphic tormulae ; all methods, hints, etc.; over 

 1000 pages. Now ready. 



" B.J. ALMANAC " contains a comprehensive treatise 

 on " Photo-Micrography," by Dr. Duncan J. Reid. 

 From your flealer, 



"BRITISH JOURNAL PHOTOGRAPHIC ALMANAC. 



1915." A libran- -n itsell. From all pliotngraphic 

 dealers. Pi-ppr co\'er 1 /- )icl, cloth-bound 2/- net ; 

 or, post free, from the Publishers, HENRY 

 GREENWOOD & CO., LTD.. 2A, Wellington 

 Street, Strand, W C, Paper cover 1 /6 "t■^ 

 cloth-bound 2/6 >u'l. Abrnntl, 2/- and o'-. 



CLARKSON'S 



SECOND-HAND 



OPTICAL MART. 



TELESCOPES. 



,' -ifi W'ray, mount- 

 ed on massive oak 

 lath stand with 

 stretchers, hori- 

 zontal and vertical 

 movements by 

 Hooke's joint, 

 slow motions.large 

 finder, 4 astro, and 

 I da\- eyepieces - - £40 



ll.Negretti 

 & Zambra aha/-, 



tuider. I .lav, -. 



4-1 



a^tros., in case .. .. 25 o o 



3i-iii. Baker, on altaz. stand, horizontal 



and vertical motions, finder, day and 



2 astros. .. .. .. ..17100 



3i-in. Dollond, on aliaz. siani.1, finder, da>- 



and 2 astros. . .. ... 12 10 O 



3-in. Steward, on altaz. with equatorial 



(undivided circles), i day, 2 astros. .. I I 10 O 

 j-in. Wood, I ;istro. and r dav eyt;pit;ces . 4 o O 



Manyotherj.. AK" !''.\'-pi*-i ■--., i'lu-i-Ts, Diasonals, etc. 



MICROSCOPES. 



■ S 15 o 



Handle Model. 



8 8 



6 15 



Watson '* Edinburg^h 



Student's *' llimn.u- 



lar, 3 eyepieces. 2-iii., 



i-in., A-in., polari- 



scope, and case 

 Watson " Hdinburgh 



H," 2/3, 1/6, 1/12 o.i., 



2 eyepieces, triple 



riosepiece, and Abbe 

 Baker "D.P.H." Stand, 



triple nosepitfce. Abbe, 



and case 

 Beck's Lartje '* London" 



spiral, Abbe and iris, triple iiosepiece, 



2 eyepieces, 2/3 and 1/6, as new , . 

 Watson "Fram," eyepiece, spiral. 



Abbe and iris, double nosepiece, 2/3 



and 1/6 

 Beck Small "London," spiral, Abbe 



and iris, double nosepiece, 23 and 1/6 6100 

 Swift "Discovery," eyepiece, 2/3. 



1/6, doubl'.- nosepiece .. ' ., ., 5 1 5 o 



Baker Student, eyepiece, A and D 



Zeiss objectives, double nosepiece .. 5 10 O 

 Bausch & Lomb Student, i eyepiece 



double nosepiece, 2/3 and 1/6. - . . S O O 



Many others. AKo Objectives (a large stock by all ihe 

 leadnig makers), Eyepieces, Double and Triple Nose- 

 pieces, Condensers, Lamps, Spectrosropes, Microtomes, 



PRISM BINOCULARS 



BY 

 ROSS, ZEISS. 

 GOERZ, etc., 



FOR SALE 



AND 

 WANTED. 



338 



HIGH HOLBORN 



(Opposiic C,i.:\\ Inn Recall, 



LONDON. 



MICROSCOPY. 



SPECIALLY ATTRACTIVE SLIDES 

 FOR POPULAR EXHIBITION tV: STUDY. 



Zoology. Marine and Freshwater.— 



Unique preparations, i.vithoi(t pyfssityc, in their natural 

 form and beauty for Dark Ground (or transparent). 

 Zoophytes^ Medus(P, Polyzoa, with their glorious array 

 of tentacles; Holothurians with wheel plates, etc. ; a 

 series of the curious Salptp and other Tunicates ; young 

 (j-<'(^/£\v developing in their eggs ; the celebrated Lance- 

 let ; also the Radiolarian Spluprozouin, the " Volvox of 

 the sea," etc., etc. 



Insects and Parts. — V.a.r\B.oi Plumed Gnat 

 (also for polariscope). Superb tongues of the rare 

 Sylzian IVasp and Hornet, also piercing organs of the 

 Cacl^y, etc., etc. 



Specia 



Cements. Forceps, Scissors, etc., 

 Mounlin-ii and Dissecting- 



for 



SECOND-HAND 



INSTRUMENTS, 



OBJECTIVES, &c. 



NEW LIST 



NOW READY. 



Post free on request. 



To Beginners.— K.xpert advice freely given 

 on selection ■.>f snUaMe equipment; much time and 

 neeilless expense ^:an thereby be saved. Write or call. 



UfAMTCn Microscopes, Objectives, etc., or whole 

 ttwn ii-MJt Outfits purchased for Cash. 



KXCHANGES MADE. 



CLARKE & PAGE, 



23, Thavies Inn, Holborn Circus, LONDON. 



LIVING SPECIMENS 



FOR THE 



MICROSCOPE. 



Volvox globator, Desnilds, Diatoms, Spirogyra, 

 Aniceba, Actinophrys. Spongilla, Vorticella, Stentor, 

 Hydra, Cordylopohra, Stephanoceros. jMelicerta. 

 Polyzoa. and other forms of Pond Life, Is. per tube, 

 with printed drawing, post free. Thomas Bolton, 

 Naturalist, 25, Halsall Heath Road, Birmingham. 



MINERALS 



FOR ALL PURPOSES 



I N ( r r 1 ) I N . . 



Experiment, Wireless, Incandescent Mamies, 

 Radio-Active, Steel Making, &c., &c. 



JAMES R. GREGORY & Co., 



Mineralogists, &c., 



139, Fulham Road, South Kensington, S.W. 



Telephone : Westerii •J,S41. 

 Telegrams: "Meteorites, Loiulon." 



SECOND-HAND DEPARTMENT. 



Microscopes, Telescopes, Spectroscopes, 

 Binoculars, Surveying Instruments, &c., 



BY THE BEST MAKERS AT MODERATE PRICES. 



Lists sent post *ree on request. 



Scienh'/Ic lnst>ui'!i->its Bou^'il. E.i\h.i>i^^t\i and Sold 

 on L onuHisshin. 



JOHN BROWNING, 



146 STRAND, and 72 New Oxford St., 



LONDON. 



1 elegranis ; 

 'AUK.S," LONDON. 



leltiphone 

 8:i4 GKRRARD. 



Established i760 



Stevens' Auction Rooms, 



38, KING ST,, COVENT GARDEN, LONDON, W.C. 



Every Friday at 12.30, Sales are held at the 

 Rooms of MiCKOScopES and Slides, Tblescopes, 

 Surveying Instkuments, Electrical and Scien- 

 tific Apparatus, Cameras and Lenses, Lanterns 

 AND Slides, Cinematographs and Films, in great 

 variety. Lathes and Tools, Etc. 



(Joods may be sent for inclusion in early Sales. 



Settlements made one week after disposal. 



Catalogues and all Particulars Post Free. 



Valuations fur Probate or Transfer, and Sales cnn. 



dueled in any part of the Ciiuntr>. 



Minerals, Rocks, Fossils, Metallic 

 Ores, Rough Precious Stones, &c. 



A Large Assortment from all parts of the world always 

 on view, and at all prices. Inspection invited. 



Crude Mineral for Chemistry Students 



aad TechiiJcai Sctools. 



Single Cystals and Teaching Specimens m Great Variety. 



RICHARDS' SHOW ROOMS. 



48 Sydoey Street Ftilbam Road, South Keasington, 

 London, S.W. 



rRicii Lii r^ I Ri I 



F. WIGGINS & SONS, 



102, t03, 104, Mmories, LONDON. E 



Contractors to H.M 

 Government 



FOR 



LAMPS, 



STOVES. 



VENTILATORS, 



ELECTRICAL WORK 



AND ALL PURPOSES. 



Largest Stock in the World. Tel. No. 2248 Avenue. 



Printer of 

 " Knowledge," 



JOHN KING, 



Uxbridge, Southall, and Ealing, 



T s favourably equipped for the PRINTING of 

 *■ Scientific Books, Brochures, Catalogues, .S;c., and 

 will be pleased to submit estimates. 



Address all Communications to 



213, UXBRIDGE ROAD, EALING, LONDON, W. 



■Plioce: 1144 EaliOfi- 



Binding Cases for Knowledge Volume, 1914. 



IN BLUE CLOTH, WITH GILT DESIGN AND LETTERING. 



!s. '.lit. net each; by Post, 2s. 



KNOWLEDGE OFEICE, ,\veiuie Chainbers. Bloomsbiirv Square, Lnmlcn, W.C. 



A most acce/ttable Gift at any time 



KNOWLEDGE VOLUME FOR 1914 



Containin^i 440 Pa^es "itli 425 Illustrations, many being Full Page Plates. 



Boiiini ill Rliip Cj-itii, (hIi [i..--,i-ti .ni.l 1 ,r:i fri in u , 15,- lit.-!, prist free within the United Kin-iloni. 



Publishing Office: AVENUE CHAMBERS, BLOOMSBURY SQUARE, LONDON, W.C, or through any Bookseller. 



