Microlepidoptera (mikrolepidoptera)

pl. [NL., If things are to be scanned so micrologically . Lowell , Among my Books, 2d ser., p. 277, note. micrology1 (mi-krol'ō-ji), n. [ μικρός , small, + -λογία, λέγειν , speak: see -ology . Cf. micrology2.] That part of science which is dependent on microscopic investigations; microgra raphy. micrology2 (mi-krol'ō-ji), n. [ Robberds , W. Taylor, II. 146. (Davies.) micro metrically branch, as a fresh-water mu el, divides; the so-called "animal cell" of Rabl, which further subdivides into blastomeres. See macromere. The segmentation resembles that of other mollusks, the micromeres appearing at the formative pole by separation of the "protoplasmic" portion of the "macromeres." Roy. Micros. Soc. Jour., 2d ser., VI. ii. 224. Micro meri a (mi-krō-mēʻri-ä), n. [NL. (Bentham), IMG:content-0592.png:[blocks in formation] angle by measuring the are that subtends it upon a circle vertex of the angleet Thus, a mirror turning through a Oblique measurement (see diagonal scale, under diagonal) ascertains a length by measuring the distance at which it subtends a small fixed angle. Thus, the wedge - micrometer is a long wedge-shaped piece of metal or gla with its slop sides as truly plane as po ible, and graduated along its lengthes it is used to measure the distance between two points having a rigid circuitous connection, but a vacant space about the line between them. The wedge being thrust between the points, the distance it penetrates shows how far apart they are. The principle of oblique measurement is, in nearly all micrometers, applied under the form of a fine screw, the number of whose revolutions and parts of a revolution, in advancing from one point to another, measures the amount of this advance. In this case the pitch of the screw is the fixed angle, while the reading of the screw-head is proportional to the variable radius at which this angle is subtended by the length to be measured.Annular or circular micrometer, a micrometer consisting, in its most approved form, of a disk of parallel plate gla , having in its center a round hole to the edges of which a ring of metal is cemented and afterward truly turned in a lathe. The disk being mounted in a bra tube, so that it may be accurately adjusted in the focus of the eyepiece and applied to a telescope, the metal ring is alone visible, and appears as if suspended in the atmosphere, whence the instrument is called the suspended annular micrometer. Brande and Cox, Dict., II. 516 (changed). - Double-image micrometer, a microm eter having an optical apparatus which produces two images of every object, as A and A', B and B'. Then, A may be brought into coincidence with B', or B may be brought into coincidence with A', and the position of the parts producing the double image will then show the distance between A and B. Filar micrometer, a microm in which objects whose distance is to be measured are brought into coincidence with two spider lines in the principal focus of a telescope or microscope, one of these webs being movable by turning a micrometer The astronomical filar micrometer is also provid screw. ed with a graduated position-circle, apparatus for illumination, etc. Micrometer-balance, a form of balance adapted to the exact determination of very small weights or differences in weight. That devised by Kershaw for testing the weight of gold pieces consists of a steelyard IMG:content-0593.png:[blocks in formation] taining to the micro lepid opters.