The microscope and its revelations . kromatic condenser,Polarizing apparatus, ]\Ecrometer eye-piece, Stage-movements,&c.; in the arrangement of which accessories, much skQfnlcontrivance is sho\yn.—The Binocular Microscope of the sameingenious Optician \Yill be described further on (§ 40). 34. Smith and Becks Studenfs Microscope.—Of the patternsyet devised for a mi-croscope of simple Fig. , whichshall yet be capableof answering everyessential purposewhether of displayor of investigation,that of and Beck ap-pears to the Authorto be (to say theleast) among thebest; and
The microscope and its revelations . kromatic condenser,Polarizing apparatus, ]\Ecrometer eye-piece, Stage-movements,&c.; in the arrangement of which accessories, much skQfnlcontrivance is sho\yn.—The Binocular Microscope of the sameingenious Optician \Yill be described further on (§ 40). 34. Smith and Becks Studenfs Microscope.—Of the patternsyet devised for a mi-croscope of simple Fig. , whichshall yet be capableof answering everyessential purposewhether of displayor of investigation,that of and Beck ap-pears to the Authorto be (to say theleast) among thebest; and he recom-mends it with themore confidence,since he has formany years em-ployed one of theseMicroscopes as hisown icorking instru-ment. There is no-thing distinctive inthe tripod support,or in the mode inwhich the micro-scope itself is sus-pended between theuprights. But thebody rests for agreat part of itslength upon a limbof solid brass,ploughed into agroove for the re-ception of the rackwhich is attachedto the body; this. Smitli and Becks Students Microscope. 88 COKSTETJCTION OP THE MICEOSCOPE. groove being of such a form, that the rack is firmly held in it,whilst it slides smoothly through it. The great advantage of thismethod of construction over any other in which the rack-and-pinion movement is made to act directly on the body, is that itrenders impossible any of that twist which tends to throw theobject more or less completely out of the field, and secures thatexact centemig which is essential to the optical perfection ofthe instrument. The upper end of the body is furnished witha draw-tube, by which its length can be increased; and oneside of this is graduated to inches and tenths. The advan-tages of this arrangement will be explained hereafter (§ 43).The fine adjustment is effected by means of a milled-head,situated just behind the base of the stem that bears the limb;this acts on a screw, the turning of which (by a contrivancethat need not be described in detai
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