1883] 



MICROSCOPICAL JOURNAL. 



227 



lent stands wliijh are sold at \erv 

 reasonable prices. It is not improb- 

 able that Mr. Crouch will, before long, 

 appoint an agent in this conntry for 

 the sale of his microscopes. His stands 

 are all made on the same premises vviih 

 his shop, the upper floor being devoted 

 to grinding th3 lenses for objectives. 

 Every stand sent from Mr. Crouch's 

 establishment passes through his own 

 hands for examination and approval. 



We were so unfortunate as not to 

 find Mr. Powell, of the firm Powell (S: 

 Lealand, when we called upon him 

 just previous to our departure from 

 London, and hoped to have- seen 

 s )me of the latest results of his han ii- 

 work. However, we had previously 

 met Mr. Powell several times, and the 

 disappointment was not so great as it 

 would otherwise have been. For fine 

 objectives, of wida angle and high- 

 power, Messrs. Powell & L;aland 

 stand clearlv at the head in Great 

 Britain, and Mr. Powell, being a most 

 excellent worker with the microscope, 

 is one of tha few persons in the trade 

 who does not hesitate to give ocular 

 demonstraUon of the excellence of his 

 lenses. 



In visiting the establishment of 

 Messrs. Svvift & Son, we were mich 

 •impressed with th_* excellence of the 

 microscopes made by them, and 

 especially wi.h the ingenuily wi:h 

 which they are designed. Thi last 

 mentioned feature is especially notice- 

 able in the latest form of the sul)- 

 stage and condenser. When the 

 original form of condenser was de- 

 scribed by Dr. Carpenter in his book 

 on the microscope, it seemed to us a 

 most excellent contrivance. In its 

 present form, as supplied to the best 

 microscopes, wc have no hesitation in 

 expressing the belief that it is, in 

 every respect, the most perfect, com- 

 plete and convenient apparatus for 

 illumination that has yet been devised. 

 There is nothing else, so far as we 

 now recollect, that comes so near our 

 ideal of what is required for tha pur- 

 pose. We have often thought it strange 

 that something: of a similar kind was 



not applied by other makers of stands. 

 Now that we have seen the thing it- 

 self, we are at a still greater loss to 

 understand the reason. Having said 

 this much, we can scarcely do less 

 than give a somewhat extended de- 

 s:ription of the apparatus which is il- 

 lus. rated in fig. 43. 



Fig, 43. — Swift's AcROMATic Condenser. 



Referring to the illustration, it will 

 be seen that the condenser consists of 

 the compact, achromatic, optical com- 

 bination at A consisting of three 

 lenses, the upper and middle lenses 

 single, the lower a combination which 

 corrects the aberrations of the others. 

 The upperlens is fitted over the others 

 in a sliding cap, so as to be readily 

 taken off if desired. Mr. Swift claims 

 that the condenser is more perfectly 

 corrected than others of a s.milar kind. 

 Our readers will doubtless remember 

 that we have, at various times, written 

 disparagingly of the achromatic con- 

 denser, regarding it as a very costly 

 accessory, of no great udlity for or- 

 dinary use. These remarks, however, 

 only apply to the old forms of achro- 

 matic condensers having very small 

 front lenses. It will be seen from the 

 figure that in the form now under con- 

 sideration the front lens is quite large, 

 and affords an abundance of light with 

 a large angular aperture. This form 



