MEMORANDA. 201 



effected by means of an ingenious yet simple sort of jointed 

 lever, Avhicli really in great measure supplies all that can be 

 done "svitli a moveable stage. But the most remarkable part 

 of the instrument is the combination of object-glasses, three 

 in number, from, we believe, an inch np to a quarter-inch, so 

 consti'ucted that when combined they constitute a really 

 excellent quarter, whilst the simple removal of the end lens 

 leaves a combination equal to a half-inch ; and the removal of 

 the second leaves the inch or lowest power. The only defect 

 we have remarked in the working of these powers is in the 

 middle or half-inch combination, which appears to require 

 still some adjustment to render it as good as the other two, 

 and Avhich might probably be effected by shutting off some of 

 its aperture after the removal of the quarter lens. The in- 

 strument is capable of being adjusted as a binocular, and on 

 the whole may be regarded as a favorable specimen of the 

 advance made in cheap, and at the same time good micro- 

 scopes since 1851. 



As we have before observed, several provincial opticians 

 have eminently distinguished themselves on the present 

 occasion, among whom may be named, Mr. Dancer, of Man- 

 chester^ who exhibits a very good form of binocular micro- 

 scope, with a refracting achromatic prism and symmetrical 

 bodies. This is a very neat instrument to look at, and all its 

 arrangements appear to be excellent; but with respect to 

 its optical performance, as we have not had an opportunity 

 of testing it, we are unable to express any opinion. We must 

 also notice the microscopes exhibited by Parkes and Co. 

 of Birmingham, who show an almost infinite variety of in- 

 struments, all well finished and well constructed, and at 

 such extraordinarily low prices, that if their performance, 

 even as stands merely, is at all commensurate with their 

 appearance, they seem to us to be marvellously cheap. 

 Among them we remark one with a magnetic stage, well 

 deserving of notice, and especially note a simple and com- 

 pound dissecting microscope, which appears a very useful 

 form of instrument. Mr. Field whose cheap microscopes, 

 it will be remembered, gained the recommendation of 

 the Society of Arts, also appears in force. In the same 

 department of popular instruments should also be noticed 

 those exhibited by Mr. Highly, very neat and useful instru- 

 ments, and well adapted for medical purposes. Nor can we 

 pass over the ingenious portable microscopes shown by Dr. 

 Eeale, and in which simplicity of construction is combined 

 with great utility and convenience as clinical instruments. 



On the whole, English opticians may well be proud of the 



