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^[[2]]

tion of the plate may be brought under the microscope, and any number of objects arranged thereon be brought into the field in succession. the objects being enclosed in the box are secure from injury; the movement of the microscope for focal adjustment is limited by stops so that the object cannot be entirely lost to view; the eye-pieces are screwed in so that they cannot be stolen, and the instrument is practically safe from everything but malicious mischief. Special mounts are required in order to increase the carrying capacity of the stage, and for transparent objects the stage must be perforated in order that the light may pass upward from the reflector below. The instrument now in use in the Museum ([[strikethrough]]See illustration[[/strikethrough]] ^[[Plate 2]]) was made in the year 1890, has been modified in a few details since, and has successfully endured manipulation by thousands of expert hands--of children as well as adults--without injury, and this without attendant supervision of any kind.

For the purpose of exhibiting a series of preparations mounted in the usual way upon glass slips or "slides", an entirely different form of apparatus has been devised. ^[[(Plate 3 & 4)]] An indefinite number, from 10 to 100, of slides are attached to an endless band of linen by means of thin brass holders which allow the slides to be changed when desired. This linen band passes over two rollers mounted upon a light brass frame which occupies the place of the "stage" of an ordinary microscope. ^[[The loop of the band hangs free.]] One of the rollers has a projecting pivot with a milled head by means of which it may be rotated, and the two rollers are connected by a narrow belt at each end. As the rollers are made to revolve the band carrying the slides passes horizontally under the microscope, resting meanwhile upon the two narrow belts, and being kept at a definite distance from the objective of the microscope by two guides which press upon the slides