KALEIDOSCOPE. 



415 



f .ilddo- of trees and shrubs, bunches of flower*, horses and cat- 

 tle in a park, carriages in motion, the currents of a 



""" ~" " river, moving insects, and, in short, every object in na- 

 ture may be introduced by the aid of the lens into tiie 

 figures crested by the instrument. 



In order to mark with accuracy the points on the 

 tube AB, suited to different distances, the instrument 

 should be directed to a straight line inclined like m n, 

 Fig. 3. to the line bisecting the angular aperture AOB, 

 and brought near to the centre O of the field. The 

 perfect junction of the reflected images of the line at 

 the |K>mt- m', : , ,\r. so as to form a star, or a polygon 

 with talient and re-entt ring angles, will indicate, with 

 great nicety, that the tube has been pulled out the pro- 

 per length tor the given distance. In thi- way a scale 

 tor dtriei-' ces, and scale* tor ditfereut lenses 



may be marked on the tube. 



When the length of the reflecting plates is leas than 

 the di.unce at which the eye sees object-, with distinct- 

 ness and without exertion, which may often be the case, 

 it U of great advantage to have a convex lem placed at 

 the eye end B ot'the rvflecti.rs. This lem should in ge- 

 neral have a focal length greater than the length of the 

 reflector, though the pattern will l>e seen with extreme 

 distinctness when the-e two length- are the same. 



The compound kaleidoscope, in the limn now ilv-cnb- 

 ed, will be found nearly sufficient for all the purposes 

 of amusement ; but for the -.ike of tho-e who may wish 

 m greater variety of object plat.--, it i- litvd up in a very 

 elegant manner, with plated ork. in a box 

 taiiu the instrument, the cell, the lrn, twelve 

 plates, and a mirror box for the purpose of holding 

 ll MI nil of coloured glass, or other objects. 



mugh a skilful artiit will have no difficulty in 

 sketching a pattern from the prrceii .merit 



when held in his hand, yet it U obviously of great ad- 

 vantage to place the instrument en rtand, M shewn 

 in I re the quaquaversus motion is obtained 



by a ball and socket, and where the instrument is cap- 

 able of being raised or depressed by two drawing tubes 

 whicli rise out of the outer tube MS. With I 

 ttrument, the patterns created either from near or dis- 

 tant objects can be rendered steady, so that the obser- 

 ver can either copy them with the utmost care, or apply 

 to the end of the instrument the armTa /xci'/n, invent- 

 ed by Dr. Wollaston. Some oftbee instruments with 

 tands arc accompanied with a spare tube for giving a 

 rent pattern by means of reflectors placed at a diffe- 

 rent an. 



The kaleidoscope, in the different forms in which it 

 has been described, U fitted up m Mich a manner that 

 >y be taken to pieces and frrrd from the du-t which 

 U apt to collect upon the reflectors. In order to do 

 unscrew the brass end N of the outer tube MN, 

 and the tube OM In-ing pu-hed in, its nl.j.rt end will 

 be exposed to view. When the ring of leather which 

 keeps the reflectors together is Clipped off, they may 

 be taken out, and carefully ip.-d with a piece of 

 clean wah leather. When . ,e, their extre- 



must be placed in the re!! from which they were 

 removed, and fixed there, < k wedges, 



or the other means which are adopted !. .-pose, 



the greatest care being . ut the same edges in 



contact. The leither ring being ,j>on the re- 



flectors, they must then be placet! in the tube OM as 

 before. A little practice will render this opor.ition ex- 

 tremely easy to any person of ordinary ingenuity. The 

 greatest care, however, must always be taken to make 

 a fine' point, or to keep the edges of the reflectors close 





together at that part which forms the centre of the 

 field of view, and to have no pressure upon the re- 

 flectors, which is capable of bending them ; for when 

 this is the rase, the beauty and symmetry of the pattern 

 U greatly injured. 



Different ways of fixing the reflectors so as to be 

 easily separated and replaced at the proper angle, have 

 been adopted in different instruments. One of the 

 most convenient is to support the reflector in a groove 

 cut out of a solid cylinder of wood of nearly the same 

 diameter as the interior diameter of the tul>e AB. This 

 grooved cylinder goes tightly into the small tube which 

 carries the angular aperture and plane glass at A ; and 

 alter a slip of wood, or any other substance, is placed 

 along the open edges of the plates, to keep them at the 

 proper angle given by the groove, the whole is slipped 

 into the tube AB, where it remains firm and secure 

 from all accident. 



SECT. VII. On the Conttruction and Use of the Polij- 

 angultir K<ilei:ioscnj>e, in which the Reflecting Planes 

 can tie fixed at any angle. 



In all the preceding instruments, the reflecting planes 

 are fixed at an invariable angle, which is some even ali- 

 quot part of" a((^ ; and therefore, though the forms or 

 pntterns which they create are literally infinite in num- 

 I.er. \.t t!:r\ Icive all the same character, in so far as 

 they are composed of as many pairs of direct anil in- 

 verted images as half of the number of times that the 

 inclination ot'the reflectors is contained in "Off. 



It i< therefore of the greatest importance, in the ap- 

 plication of the kaleidoscope to the arts, to have it con- 

 structed in such a manner, that patterns composed of 

 any number of pairs of direct and inverted images may 

 be created and drawn. With this view, the instrument 

 may befitted up in various ways, with pper, cloth, and 

 metallic joints, by means of which the angle can be va- 

 ried and fixed; but one of the most convenient methods 

 U shewn in Fig. 8, which represents the instrument p tAT E 

 as made by Mr. Bate, optician. London. CCCXLI. 



This instrument is composed of two cones M, N, Fig- 8. 

 connected together by a middle piece or ring below R, 

 into which they are both screwed. These lines enclose 

 two highly polished metallic reflectors AO, BO, one of 

 which BO is fixed to the same ring below R, to which 

 the two cones are screwed, and is so adjusted by -crews 

 that its reflecting surface passes through the axis of the 

 cones and rings. The other n Hector AO is fixed to the 

 outer ring R by an arm passing through an annular 

 space or arch of a little more than 90 cut in the cir- 

 cumference of the inner ring, and while its reflecting 

 surface is adjusted so as to pass through the axis of the 

 cones and rings, its lower edge OM M . is finely ground 

 to a perfectly straight line, free of all roughness ; and 

 this edge is so adjusted by screws that it coincides with 

 the axis of the cones and ritiL";. The lower edge of 

 the reflector AO comes a little below the same axis, 

 to that the edge OE of the reflector BO just touches a 

 line in the reflector AO, which coincides with the axis 

 of the cones and rings, and forms a junction in every 

 part of the two meeting edges. 



If we now fix the outer ring R into the ring of a stand 

 ST, so as to be held fast, and turn the cones M N with 

 the hand, we shall give motion to the reflector BO, 

 so as to place it at any angle we please, from O 9 to 90 ; 

 and during its motion through this arch, the junction 

 of the two reflectors must remain perfect, if the touch- 

 ing Hoes are adjusted, as we have described them, to 



