June 8, 1905] 



NATURE 



The 



Typewriter 



for 



Beautiful Work. 



YOST 



S^vift, Quiet, and Convenient. 



Illustrated Booklet Post Free. 



The YOST TYPEWRITER CO., Ltd., 

 50 Holborn Viaduct, London, E.G. 



DR. H. STROUD'S 



Apparatus for 



DETERMINING THE 



VELOCITY OF 



SOUND IN AIR, BY 



THE METHOD 



OF RESONANCE. 



The Resonance Tube is j ft. 

 long, with a graduated scale 

 fixed at the side. The sliding 

 reservoir moves easily in a 

 grooved frame, so that the water 

 level can be quickly altered. 



Price, in Polished Mahogany 

 Stand, 24/- 



sol.e: ivia.ke:rs- 



BRADY & MARTIN, Ltd, 



Scientific Jlpparatus makers, 

 NEWCASTLE-UPON-TYNE. 



Makers and Dealers in all kinds of Chemical and Physical 

 Apparatus for Schools and Colleges, Works' Laboratories 



and Special Research Work. 



CONSTRUCTION OF NEW FORMS OF APPARATUS 



UNDERTAKEN. 



=' Tabloid' 



Brand 



Metol-^inol 



^elJeloper. 



Equally good for plates, 

 films, bromide papers, gas- 

 light papers and lantern 

 slides. Economical and 

 compact : portable and 

 keeps. 



Sold by all dealers and chemists. 



WRITE FOR BOOKLET GRATIS. 



Burroughs Wellcome and Co., 



London, Sydney and Cape Town. 

 Ckief Offices— Snow Hill Buildings, London. 



c.„.,s»t] pho. 70 



W. IfflLSON. 



STUDENT'S SPECTROMETER. 



Telescope and prism 

 table reading to I 

 min. ; clamp and fine 

 adjustment to both. 

 Rack-motion to tele- 

 scope ; prism table 

 adjustable vertically 

 and horizontally. Ad- 

 justable slit to colli- 

 mator. Protected 



circle. In case. 

 O O 

 nts have been sold, 



Price 



£6 



epy large number of these instru 



and have given 



ptional satisfaction. 



1 BELMONT STREET, LONDON, N.W. 



Descrlpt 

 Pamphlet 

 Post Free. 



PIESMIC BAROMETER. 



To bo obtained ot all Opticians, or 

 the SOLE MAKERS. 



F. r>ARXON^ St. CO., 



CLERKENWELL OPTICAL WORKS, 



JOHN STREET, LONDON, E.G. 



