gyromata

Plural of gyroma. gyron, giron (ji'ron), n. [F. giron, a gyron, so called in reference to the arrangement of gyrons round the fe e-point; chief, and is considered to occupy one half of the first quarter; but if otherwise, its position must be stated in the blazon. gyrostatic The instrument commonly called gyroscope is better named gyroscopic top (which see, under gyroscopic ). The gyroscope proper of Foucault, shown in the figure, consists of a flywheel having the small conical bearings of its axis in a well balanced metallic ring which carries two knife-edges in a line perpendicular to the axis of the fly-wheel; these knife-edges bear upon agates carried in a horizontal plane by an outer vertical ring half suspended from a small copper wire and turning about a vertical axis. The axis of the wheel can thus turn in any direction. By means of an acce ory apparatus a velocity of 150 turns a second can be imparted to the fly-wheel. The principal experiments with this apparatus are as follows: First experiment.If, when the fly-wheel is turning rapidly, no considerable force is applied to change the direction of its axis, its direction will remain almost unchanged. For, suppose it were proposed, by an instantaneous impulse, to turn this axis round a fixed axis perpendicular to it; then, at the point where this fixed axis cuts the rim of the fly-wheel, a particle would have to be deflected, and it can be shown by the parallelogram of motions that a velocity must be communicated to it proportional to the velocity it already po e ed. Hence, the force required to rotate the axis of a fly-wheel increases with its velocity. Accordingly, when the velocity is very high, the friction on the bearings will change the direction of the axis but very little. But all the surrounding objects partake of the rotation of the earth upon its axis. Consequently, the axis of the fly-wheel will have a relative rotation; and this may be observed with a microscope. Second experiment. If the fly-wheel was attached to its axis by a so that its plane was free to take any inclination to the axis, it is plain that by virtue of centrifugal force it would become perpendicular to the axis, since in this way its particles would furthest from the axis. then the outer ring of the gyroscope be held fast in such a position that the axis of the fly-wheel is free to move in the meridian plane, it partakes of the rotation of the earth; and the rotation of the earth and that of the fly. wheel being compounded, the axis of resultant rotation is not quite perpendicular to the fly-wheel. Accordingly, the inner ring will turn on its knife-edges until the axis of the fly-wheel is brought into parallelism with that of the earth, so that the wheel revolves from west to east like the earth. Third experiment. On the same princi ple, if the outer ring be free to turn, but the inner one be fixed horizontally, the outer ring will turn so as to bring the axis of the fly-wheel into the meridian. Fourth experiment. - Let the inner wheel be thrown out of balance by hanging a weight upon it near one end of the axis; then weight instant communicate a tion about the knife-edges, compounding itself with the rotation of the fly-wheel about its axis as the rotation of the earth does in the third experiment, and a rotation of the outer ring round its vertical axis will result. Since the resultant axis of the first two rotations is very near that of the fly-wheel, the tendency of the weight to fall will be but slight, and under the influence of the centrifugal force of the third rotation it will move like a conical pendulum.-Gyroscope governor, a steam-governor in which a gyroscope is employed as a regulator. A change in the speed of the engine causes a heavy gyroscope to change its plane of rotation, this change in turn controlling the speed of the engine. See governor. gyroscopic (jī-rō-skop'ik), a. [ gyron netty, giron netty (ji-ro-net'i), a. raldic F. gironnetté, ed into a number of triangular parts of two different tinctures. The points of all the triangles meet at the fe e-point. The number of tri an tadpole, porwiggle (so called rinida. (Line shows natural size.) from its round shape), IMG:content-2851.png:[blocks in formation] gyronny of eight, or and gules. Also written gironné. Gyronny, covered with gyrons, or divided so as to form several gyrons; said of an escutcheon. Booke of Precedence (E. E. T. S., extra [ser.), i. 116. [Heraldic F. In her., divid Gyronny of eight, gules and argent. gyron wise, giron wise se (ji'ron-wiz), (ji' adv . In her ., in the direction of the lines forming a field gyronny-that is, radiating from the fe e- point. Gyrophora (ji-rof'ō-ra), n. [NL., Gyrophora (ji-rofo-ru), circle, bear1 .] A genus of lichens, one of which is the tripe -de-roc he. gyrophoric (jir-ō-for'ik), a. [ Gyrophora + -ic .] Belonging to or derived from plants of the ge- nus Gyrophora : as, gyro- phoric acid. gyroscope (jirō-skōp), n . [= F. gyroscope , a name given in 1852 by Foucault to his improved form of Bohnenberger's appara- tus, γύρος , a circle, + σκοπεῖν , view.] An in- strument consisting of a fly-wheel, the axis of which can turn freely in any direction, designed to illustrate the dynam- ics of rotating bodies. Foucault's Gyroscope. The bearings are of great length and large diameter to stand the gyroscopic action which occurs in a heavy sea on board ship. The Engineer, LXVI. 364. Gyroscopic pendulum, an instrument consisting of two piensersal hich the first is attached to one of the axes of flexure joint, the other axis being held fixed; while the second piece is jointed to the first by an axis parallel to the fixed axis of the universal flexure joint. - Gyroscopic top, an instrument consisting of a heavy fly-wheel revolving about an axis one point of which is fixed, but which is otherwise free to move in any way. The fly-wheel being set in rotation, the axis moves about the fixed point in the manner explained under gyroscope, fourth experiment. Gyroscopic Top, or Gyroscope. IMG:content-2852.png:[graphic] IMG:content-2853.png:[blocks in formation] IMG:content-2854.png:[blocks in formation] IMG:content-2855.png:[ocr errors] IMG:content-2856.png:[merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small] OPP s.Oc B Мос plied to le er divisions of the surface of the brain, is not gyst2t, n. always preserved. Gyrus is exactly synonymous with volution . - Angular gyrus, a certain gyrus of the hem i gyst3t, n. sphere of the brain in man and monkeys. In man it is gyst-ale, An obsolete form of gist , now joist . An obsolete form of gest2 . gyri, separated by a short vertical sulcus from the supra- superior temporal fi ure, the hindmost one of four parietal marginal gyrus. See fig. 3, and cut under cerebral . - An- nectent gyrus, a small or secondary fold, which may con- nect larger or primary convolutions: especially applied to several such gyri of the occipital lobe, as those forming the connections of the cuneus or occipital lobule. See cut under cerebral . - Arched gyri, four arched convolu- tions regularly arranged, in some carnivorous animals, as the dog and wolf, beginning with one which borders the Sylvian fi ure and ending with one which forms the mar- gin of the cerebral hemisphere. They are enumerated from first to fourth , as by Leuret, or in reverse order (Ferrier), or only three are recognized (Flower), when they are also called inferior , middle , and superior (Mivart). - Ascend- ing frontal gyrus, the gyrus bounding the fi ure of Rolando in front. Also called the anterior central gyrus and transverse frontal gyrus . See cut under cerebral . - Ascending parietal gyrus, the gyrus bounding the fis- sure of Rolando behind. Also called the posterior central convolution . - Callosal gyrus, a convolution of the me- dian surface of the cerebrum immediately over the corpus callosum and below the callosomarginal fi ure. It is con- tinuous behind with the gyrus hippocampi, and ends in the gyrus uncinatus. Also called convolution of the corpus callosum, and gyrus fornicatus , from its arched or forni- cated figure. See cuts under cerebral and sulcus.- Cu- neate gyrus, a convolution of the occipital lobe appear- ing as a wedge-shaped figure on the median aspect of the cerebrum in the fork between the parieto-occipital sulcus and the calcarine sulcus. Also called occipital lobule and cuneus. See cut under cerebral . - External orbital gy- rus, that part of the orbital surface which lies outside of the triradiate sulcus. Gray. Frontal gyri, three gyri which compose the superior and lateral surface of the fron- tal lobe of the cerebrum, all lying in front of the ascend- ing frontal gyrus. They are defined by the superior and central sulcus. - Gyrus fornicatus. Same as callosal gyrus. - Gyrus quadratus, the quadrate gyrus. - Hip- pocampal gyrus, the continuation of the gyrus forni- cat us where it dips down behind and below the corpus callosum, and continues forward to the uncinate gyrus: so called from its relation to the hippocampus. - Marginal gyrus. (a) That part of the first frontal convolution which appears on the median side of the hemisphere. See cut under cerebral . (b) The gyrus which arches over the ex- tremity of the fi ure of Sylvius. See sulcus. - Occipital gyri, three principal convolutions of the occipital lobe of the cerebrum, separated by two small transverse sulci, and distinguished as first , second , and third , from above down- ward, or, as in fig. 3, superior , middle , and inferior . See cut under cerebral . - Orbital gyri, the gyri or convolu- tions upon the under or orbital surface of the frontal lobe of the cerebrum, which rest upon the orbital plate of the frontal bone. They are three in number, directly contin- uous with and corresponding to the frontal gyri. The two best-marked orbital gyri are sometimes distinguished as the internal and external . - Parietal gyri, four well-marked convolutions upon the superior and lateral surface of the parietal lobe; and especially two of these distinguished as the ascending parietal (or posterior central) and the superior parietal , the other two being commonly known as the supra marginal and the angular gyrus . (See other phrases.) In fig. 3, the superior parietal is called postero- parietal lobule . - Quadrate gyrus, a convolution of somewhat square figure appearing on the median surface of the cerebrum between the callosomarginal sulcus in front and the parieto-occipital sulcus behind, and contin. nous below with the gyrus fornicatus. Also called quad- rate lobule and pre cuneus . See cut under cerebral . - Sig- moid gyrus, the somewhat S-shaped fold which curves about the lateral end of the cruciate fi ure, and whose surface includes several constant and well-marked "mo- tor areas": used especially by English writers. - Tem- poral gyri, in fig. 3, a general name of the temporal con- volutions: usually in human anatomy more fully called temporosphenoidal gyri. - Uncinate gyrus, a convolu- tion which appears on the median surface of the cerebrum nearly opposite the beginning of the gyrus fornicatus. It is so called from its shape, and the hook is known as the crotchet or uncus . See cut under cerebral . difficulties which have thus far been insurmountable ex- cept in the cases of the most constant and best-marked folds and fi ures. (See the cuts.) Additional difficulty is encountered in the fact that different human brains vary in details of the gyri, and the same brain may differ on its opposite sides. The principal gyri are noted in the phrases below. The gyri represent an enormous increase in quantity of the gray cortical matter or cortex of the brain in comparison with the actual superficies of the cerebral hemispheres, some of the folds being separated by fi ures an inch or more in depth, and containing three layers of gray matter with three layers of white. The gyri are to some extent an indication of intellectual power, and are better marked when the mental powers of the ind i- vidual are at their height than in infancy and senility. The distinction between gyrus and lobe or lobule , as apgyst1t, n. A Middle English form of guest . extra at with allusion to festive mummery.) See the gyte2 (git), n. [Another form of gait , gayt , etc., for get1 , n., offspring, a child: see get1 , n.] 1. A child: generally in contempt.-2. A first year's pupil in the High School of Edinburgh. [Scotch in both senses.] gytrash (gi'trash), n. [Origin obscure.] A spirit or ghost. [Prov. Eng.] the form of horse, mule, or large dog, haunted solitary ways, and sometimes came upon belated travellers. Close down by the hazel stems glided a great dog, whose black and white color made him a distinct object against the trees. It was exactly one mask of Be ie's Gytrash- a lion-like creature with long hair and a huge head. Charlotte Brontë, Jane Eyre, xii. gyve (jiv), v . t .; pret. and pp. gyved , ppr. gyving . [Also written give ; given , gyven , fetter, gyres , gives , pl., fetters: see gyres .] To fetter; shackle; chain; manacle. [Poetic or archaic.] I will gyve thee in thine own courtship. Shak ., Othello, ii. 1. She had gyved Them so in chains of darkne , as no might Should loose them thence. One hair of thine more vigour doth retain To bind thy foe, than any iron chain: Who might be gyv'd in such a golden string, Would not be captive, though he were a king. IMG:content-2857.png:[merged small][ocr errors][merged small][merged small][merged small][merged small] The Century Dictionary and Cyclopedia: Dictionary IMG:content-2859.jpg:[graphic][subsumed][ocr errors][ocr errors][subsumed][ocr errors][subsumed][subsumed][subsumed][subsumed] The Century Dictionary and Cyclopedia: Dictionary About this Book - From This is a copy of a book that was preserved for generations on library the world's books discoverable online. It has survived long enough for the copyright to expire and the book to enter the public domain. A public domain book is one that was never subject to copyright or whose legal copyright term has expired. Whether a book is in the public domain may vary country to country. Public domain books are our gateways to the past, representing a wealth of history, culture and knowledge that's often difficult to discover. Marks, notations and other marginalia present in the original volume may appear in this file - a reminder of this book's long journey from the publisher to a library and finally to you. the most basic level is based on page images of the physical books. To make this book available as an ePub formated file we have taken those page images and extracted the text using Optical Character Recognition (or OCR for short) technology. The extraction of text from page images is a difficult engineering task. Smudges on the physical books' pages, fancy fonts, old fonts, torn pages, etc. can all lead to errors in the extracted text. Imperfect OCR is only the first challenge in the ultimate goal of moving from collections of page images to extracted-text based books. Our computer algorithms also have to automatically determine the structure of the book (what are the headers and footers, where images are placed, whether text is verse or prose, and so forth). Getting this right allows us to render the book in a way that follows the format of the original book. Despite our best efforts you may see spelling mistakes, garbage characters, extraneous images, or mi ing pages in this book. Based on our estimates, these errors should not prevent you from enjoying the content of the book. The technical challenges of automatically constructing a perfect book are daunting, but we continue to make enhancements to our OCR and book structure extraction technologies. We hope you'll enjoy these books as much as we do. Usage guidelines is proud to partner with libraries to digitize public domain materials and make them widely acce ible. Public domain books belong to the public and we are merely their custodians. Neverthele , this work is expensive, so in order to keep providing this resource, we have taken steps to prevent abuse by commercial parties, including placing technical restrictions on automated querying. We also ask that you: