Selection of Microscopes and Accessories. 



Manufactured by Messrs. SWIFT & SON, London. 



(Any other Microscope or Fittings of Messrs. SWIFT & SON'S make obtained to order at their 



list price). 



1373 

 Swift's Petrological Microscope. 



This instrument has lately been constructed to meet the requirements both of the advanced student and the 

 professional mineralogist. 



The coarse adjustment is by diagonal rack and pinion. 



The fine adjustment is by a micrometer screw reading to .01 millimetre. 



The rotating stage is divided on the edge and reads to 5' . 



The analyser is of the " Dick " pattern. It is fitted over the ocular, and can (together with its divided circle) 

 be swung aside, out of the optic axis. The prism is of the latest ' ' Glan-Thompson " type, and embraces a very wide 

 & riffle 



The ocular is slotted to take the micrometer, wedges, etc. It has an adjustable eye-lens to allow of the 

 accurate focussing of its cross webs. 



A Bertrand lens is fitted in the optical tube. It can be focussed and thrown in or out of the optic axis at will. 



A centring nosepiece of specially rigid design is provided. Immediately above this is a slot, with a dust 

 excluding cover, cut at 45 to the cross webs, for the reception of wedges, plates, and other compensators. 



A convergent system of lenses with an iris diaphragm is mounted on a lateral screw focussing adjustment 

 immediately below the stage. When screwed right down the whole of this apparatus automatically swings aside, 

 out of the optic axis. The top lens of the convergent system can be removed when light of very low convergence 

 is required. 



The polariser is mounted on an independent swing-out arm. The prism is particularly la^e, and will 

 than fill the field. Its mount is divided on the flange, and clicks when the prisms are crossed. 



1373' Microscope, as described, with cross-webbed, slotted ocular, in mahogany cabinet 



A. Extra Bertrand lens, at lower end of body 



B. Millimetre scale on coarse adjustment, for refractive index work, etc. 

 Millimetre scale on focussing Bertrand lens 



C. 



D. Double nosepiece 



16 

 10 

 10 

 050 

 15 



See page 274 for other accessories. 



CHEMICAL AND SCIENTIFIC APPARATUS AND PURE CHEMICAL 



273 



