The microscope and its revelations . portability, necessarilyarising from the substantial mode of its construction; and inthe multiplicity of its movable parts, which presents to thebegimier an aspect of great complexity. This complexity,however, is much more apparent than real; for each of theseparts has an independent action of its own, the nature ofwliich is very soon learned; and the various milled-heads areso disposed, that the hand readily (and at last almost instinc-tively) finds its way from one to the other, so as to make anyrequired adjustment, whilst the eye is steadily directed to
The microscope and its revelations . portability, necessarilyarising from the substantial mode of its construction; and inthe multiplicity of its movable parts, which presents to thebegimier an aspect of great complexity. This complexity,however, is much more apparent than real; for each of theseparts has an independent action of its own, the nature ofwliich is very soon learned; and the various milled-heads areso disposed, that the hand readily (and at last almost instinc-tively) finds its way from one to the other, so as to make anyrequired adjustment, whilst the eye is steadily directed to theobject. To the practised observer, therefore, this multiplica- POWELL AND LEAXAND S MICROSCOPE. 99 tion of adjustments is a real saving: of time and labour,enabling him to do perfectly and readily what might otherwiserequire much trouble, besides affording hiin certain capabilitieswhich he would not otherwise possess at aU. 38. Powell and Leakmds Compound Microscope.—Thisinstrument, represented m Fig. 28, is far Hghter than the. Powell and Lealands Large Compound 2 100 CONSTEUCTION OF THE MICROSCOPE. preceding in its general build, Mdtliout being at all deficientm steadiness; it has not, however, some of those movementsfor which Mr. Rosss plan of construction is especiallyadapted. The three-legged stand gives a firm support to thetrunnions that carry the tube to which the stage is attached,and from which a triangular stem is raised, by the rack-and-pinion movement set in action by the double-milled head,whereby the coarse adjustment of the focus is triangular stem carries at its summit the transverse arm,which contains (as in Mr. Rosss microscope) the lever-actionof the fine adjustment; and this is acted-on by the milled-head at the back of the arm, whence also pass two obliquestays, which, being attached to the upper part of the body,assist in preventing its vibration. The stage is provided witha traversing movement in each du-ection, to the exte
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