A WEEKLY ILEUSri^A i i; I) JOl KNAL OF SCIENCE 



" To the solid ground 

 Of Nature trusts the mind which builds for aye." — WoRUS worth. 



No 1878, Vol.. 72] 



THURSDAY, OCTOBER 26, 1905 



[Price Sixpence 



the General Fosl Office.) 



NEW PATTERN "NEWTONIAN" CHEAP 

 ELECTRIC LANTERN. 



5067 New Iron Bociy Lantern, «iih I'ra.-,.^ itMni, nucdor 



mahogany buani. 4-in. doulile Condenser, best full-size acliro- 



matic Front Lens, and " Newtonian " Hand-Feed Arc Lamp. 



Complete in Case £10 10s. 



3Ve:"wto3v «sc 00., 



OPTICIANS TO HIS MAJESTY THE KING 

 AND H R.H. THE PRINCE OF WALES AND THE GOVERNMENT. 



S FLEET STREET, LONDON. 



PHOTOGRAPHIC LENSES. 



A SIMPLE TREATISE. 



By CONRAD BECK and HERBERT ANDREWS. 



X -, Post Free 1/3. 



This somewhat difficult subject is made clear without 

 the use of maihematics. 



R. & J. BECK, Ltd., 68 CORNHILL, 



PRACTICAL NOTES ON 



TELEPHOTOGRAPHY. 



Free on application to 



R. & J. BECK, Ltd., 68 CORNHILL, LC 



OUR ILLUSTRATED CATALOGUE 



PHYSICAL APPARATUS 



IS 3VO-W I«,EA.I>"V. 



See Notes, "Nature," p. 518, Sept. 21, 1905. 



POST FREE TO 



PRINCIPALS & SCIENCE MASTERS. 



ALL ORDERS RECEIVE PROMPT AND 

 PERSONAL ATTENTION. 



IBT. G. I>YE <& CO., 



SCIENTIFIC INSTRUMENT MAKERS, 



GRANTA WORKS, CAMBRIDGE. 



ZZ NEGRETTI & ZAMBRA'S 

 LONG RANGE 



BAROMETERS. 



THE GLYCERINE BAROMETER. 



This Barometer has a tube containing both Mercury and 

 Glycerine. The lighter specific gravity of the latter and 

 the difference in the bore of the lube in which it rises and 

 falls increases the scale to about 8 inches for each inch of 

 the ordinary mercurial column. 



By means of this interesting instrument the smallest 

 variations in the atmospheric pressure are quite notice- 

 able, differences of looth of an inch being easily read 

 without the aid of any vernier or magnifier. 



Further Varticutars and Prices of this and other 



long range 'Barometers sent on application 



to the Manufacturers^ 



NEGRETTI & ZAMBRA, 



38 HOLBORN VIADUCT, E.G. 



■fl Branches: 45 CORNHILL, and 122 REGENT 



STREET, LONDON. 



