. The microscope and its revelations. FIG. 200.—Stephensons binocular by Swift (1887). upon the Steinheil formula, composed of three cemented lensesforming a system which gives relatively long working distanceswith large flat field. As made by Zeiss they magnify 6, 12, 20, and 250 THE HISTORY AND DEVELOPMENT OF THE MICEOSCOPE 30 times, .-mil. employed in such ;i stand ;is fig. 202, they are ad-miral ily adapted for picking out minute shells or for other similarmanipulations, the sand or dredgings to be examined being spreadupon a piece of black paper, and raised upon a book, a box, or someothe
. The microscope and its revelations. FIG. 200.—Stephensons binocular by Swift (1887). upon the Steinheil formula, composed of three cemented lensesforming a system which gives relatively long working distanceswith large flat field. As made by Zeiss they magnify 6, 12, 20, and 250 THE HISTORY AND DEVELOPMENT OF THE MICEOSCOPE 30 times, .-mil. employed in such ;i stand ;is fig. 202, they are ad-miral ily adapted for picking out minute shells or for other similarmanipulations, the sand or dredgings to be examined being spreadupon a piece of black paper, and raised upon a book, a box, or someother Mipport to such a height that when the lens is adjustedthereto, the eve may be applied to it continuously without unneces-sary fatigue. It will be found advantageous that the foot of themicroscope should not stand upon the paper over which the objectsare spread, as it is desirable to shake this from time to time in orderto bring a fresh portion of the matters to be examined into view ;. FIG. 201.—Greenoughs binocular, arranged as a dissecting microscope (1897). and, generally speaking, it will be found convenient to place it on the opposite side of the object, rather than on the same side with the obsfi-\er. In a suitable position these lenses with their holder may In- must conveniently set for the dissection of objects contained in a plate or trough, the sides of which, being higher than the lens, would prevent the use of ariy magnifier mounted on a horizontal Although the uses of this little instrument are greatly by its want of stage, mirror, Arc., yet, for the class of pur- o which it IN suited, it has advantages over perhaps every er foim that has been devised. Where, on the other hand, LENS-HOLDERS 2$ I portability may be altogether sacrificed, and the instrument is to beadapted to the making of large dissections under a low magnifyingpower, some such form as is represented in fig. 203 constructed byMessrs. Baker, on the basis of that devised by Professor Hux
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectmicrosc, bookyear1901