. The microscope and its revelations. rs paper of 1830 gave the obvious clue to a method ofneutralising this; that is to say, by lens distance ; and Ross appliedthis correction by mounting the front lens ofan objective in a tube which slid over anothertube carrying the two other pairs. A veryprimitive form of this lens correction is affordedus by a i-iiich objective made by Andrew Rossin 1838. It belonged originally to ProfessorLindley, the second President of the RoyalMicroscopical Society, and was presented to thesociety by his son, the Master of the Rolls, in1899. An illustration of this le
. The microscope and its revelations. rs paper of 1830 gave the obvious clue to a method ofneutralising this; that is to say, by lens distance ; and Ross appliedthis correction by mounting the front lens ofan objective in a tube which slid over anothertube carrying the two other pairs. A veryprimitive form of this lens correction is affordedus by a i-iiich objective made by Andrew Rossin 1838. It belonged originally to ProfessorLindley, the second President of the RoyalMicroscopical Society, and was presented to thesociety by his son, the Master of the Rolls, in1899. An illustration of this lens is given infig. 311. The tube carrying the front lensslides on an inner tube; it can be clamped inany position by the screws at the sides ; theline in the small hole in the front indicates itsposition, and is the prototype of the covered and uncovered lines of later times. The larger cylinder at the base is the lid of its box upon whichit is standing. Subsequently this arrangement was modified by the introduction 1 Vide Chapter FIG. oil.—Primitiveform of lens correc-tion (1838). 353 OBJECTIVES, EYE-PIECES, THE APEKTOMETEK of ii sereu arrangement, as in fig. 312. The front pair of lenses isfixed into a tube (A) which slides over an interior tube (B) by whichthe other two pairs are held ; and it is drawn up or down by meansof a ciillar (I1), which works in a furrow cut in the inner tube, andupon a screw-thread cut in the outer, so that its revolution in theplane to which it is fixed by the one tube gives a vertical movementto the other. In one part of the outer tube an oblong slit is seen at D, into which projects a small tongue screwed on theinner tube; at the side of the former two horizontal lines areengraved, one pointing to the word uncovered, the other to theword covered ; whilst the latter is crossed by a horizontal mark,which is brought to coincide with either of the two lines by therotation of the screw-collar, whereby the outer tube is moved upor down.
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectmicrosc, bookyear1901
