Page:The New International Encyclopædia 1st ed. v. 11.djvu/550

* KINEMATICS. 49S KINETOSCOPE. KINEMAT'ICS (from Gk. Klvrnia, kini-ma, luovtuienl, I'lum kikiv, kiitcin, to move). That branch of uiL-cliiiiiics which treats of diirerent kinds of uiotiou entirely regardless of the idea of matter and its inertia. It is therefore, strict- ly speaking, a department of geometry. See Mechanics. KINETIC ENERGY. See E.n-eegetics ; Me- chanics. KINETICS (Ok. (c(i'7(Tit:6s, kinCtikos, for putting in motion, from KivTjris, khiifos, mov- able, from Kii'cri', /.iiiriH. to move) . That branch of dyn;imic< which treat* of the question of changes ill the motion of matter, the conditions under which such changes occur, and the properties of the matter while the motion is changing. See Mechanics. KINETICS OF GASES. See Hvdrodtnam- ics. KINETIC THEORIES OF GASES. See ilATTEE. KINETOGEN'ESIS (from Gk. Kivrrrir, kinc- ios, movable + yiyici.!, genesis, origin, from ylyveaBaL, yiynesllmi. to become). The mechan- ics of evolution. .Spencer led the way to these studies by his theory of the mechanical origin of the segmentation of the body in vertebrates, lead- ing to the formation (jf vertebrae. Wyman ( IS-iT ) showed that the cancellated ^^tructure of the bones of the head, of the thigh-bone, ami in other bones is peculiar to man, liaving a delinite relation to his erect position. The bony librcs forming the cancellated structure are like studs or braces. Cope, and also Ryder, have discussed the mold- ing of the limb-joints as the result of mechanical strains, and the shai)e of the teeth is due to mechanical strains and impacts. The direct evidence in favor of the kineto- gcnctic mode of evolution is greatly strengthened by the discovery by Ameghino, in tlie Tertiary beds of the Argentine Rejiublic. of onetocd ungu- lates with two splint bones and with teeth strik- ingly like those of the horse, though belonging to a quite dilTcrcnt order. The similarity or con- vergence in shape is due to the action of similar mechanical condition.s in two quite unrelated groups. The results of strains involved in dig- ging are seen in the fore legs of the mole, of the fossori.l edentates, and the mole-crickets. Thus. as Cope concludes, in biologic evolution as in ordinary mechanics, identical causes produce identical results. Consult : Wyman, "On the Cancellated Struc- ture of .Some of the Bones of the Human Body," in the Journal of the Boston Socictii of yatiiral Histor;/. vol. vi. (Boston. 1857) ; Cope, The Pri- marii Factors of Oriianic Evolution (Chicago, 1896). See EvonTiON ; Use-1xiikkitance. KINET'OSCOPE. An instrument for pro- ducing a seiies oi iinagos in such rapid succession that the illusion of actual motion results. The apparatus as usually constructed consists of a pro- jecting lantern with an arc light as its radiant and a fine projecting lens by which the image is formed. (Sec Mac.ic Lantern.) The pictures of which the images are produced are made on a long celluloid film about one inch in breadth, and of length depending upon the duration of the series of pictures. This film contains a series of photo- graphs of a moving object made at successive intervals, and is rapidly nmved in front of the projec-ting lens by an electric motor or other rotating mechanism. There is also a revolving shutter operated by the same mechanism which moves the lilm, which alternately cuts olf and allows to pass the light between the lilm and the projecting lens. The instrument operates by al- lowing a picture on the lilm to rest for a minute interval in front of the projecting lens, during which tiuie the rays of light are allowed to pass through the opening in the shutter. The next picture on the film, representing a subsequent state in the action, is then brought before the projecting lens in the same nuiinier. The ajipara- tus is adjusted so that between 40 and 50 suc- cessive exposures of the film occur in a second, and the ell'ect of motion luoduced on the screen is wonderfully realistic. This is due to the fact that the duration of the impression furnished by light on the retina is about onc-tiltieth of a sei-oud. and if these impressions follow with suf- ficient rapidity the ell'ect is of continuous motion. This principle has been known for many years, and was first employed in the stroboscope (q.v.), where a series of slits were cut radially near the circumference of a disk. A moving body was viewed through these slits in the disk as it re- volved, and its a|>])arent motion depended upon the relative motion of the moving body and the disk. The next imjiortMut api)lication of this idea was in the zoetrope, in which a cylindrical box with a scries of vertical slits was rapidly rotated about its vertical axis. These slits ex- tended from the upjier edge of the cylinder half- way its height, and within and below was (jassed a sheet of i)aper on which were drawn a scriis of pictures showing an object in successive stages of motion. Tliis instrument, which is illustrated in the article Illcsion, was for many years mere- ly a popular toy, as it was not possible until the advent of instantaneous photography to depict objects at successive intervals sufficiently accu- rately to enable tlie instrument to be of practical or scientific vahu'. One of the earliest applica- tions of instantaneous photography to this in- stnuuent was when tlw Muybridge photographs of n:oviug objects were employed for this purpose. Here a number of cameras were so placed as to obtain in succession instantaneous photographs of a moving object. From the positives thus ob- taine<l a strip was prejiared for the zoStrope, and a lifelike re|)resentation secured. Various <le- •,<'lopments of this idea and modifications of the instrument were employed, but it was not until a special form of camera made possible by the use of sensitiwd films of celluloid was employed that practical and satisfactory results were obtained. This was accomplished by Edison in 189.3. and the camera employed used a shutter Avhich al- lowed the light to fall on the film at regularly recurring intervals. During these intervals the film remains stationary so that the exposure can be made, and is then rapidly moved for- ward so that the next exposure is permitted. The whole action of moving the film and the operation of the shutter is worked automatically. ;>nd the process has developed so that rolls of film of great length can be exposed. The film after its exposure is developed in the usual way. and then a positive -is made which is employed in the projecting lantern or apparatus used to view the pictures. Tn the first form of kinetoscope no attemjit was made to project the pictures, but they were examined by the observer through a larire maSTiifying glass illuminated from behind. It is in its application to the projecting lantern.