KALEIDOSCOPE. 



*409 



ous from the'principles already explained, that very sin- 

 gular effects will be obtained from the combination of 

 three or more reflectors. 



Kaleidoscopes may be constructed, by combining four 

 equal reflector* in the form of a hollow square, or five 

 reflectors in the form of a hollow rectangle ; but though 

 they exhibit regular figures from the angles being even 

 aliquot parts of 360*, yet they are by no means inter- 

 esting. All polygons of a greater number of sides are 

 incapable of giving regular form*, as their angles must 

 exceed any even aliquot part of a circle. It is, there- 

 fore, only from a combination of three reflectors that 

 we can expect any pleading and useful effect. 



e the angles at which the three mirrors are placed 

 must be all evrn aliquot parts of liO J , such as 90, 60, 

 +5', 36% 30', 25^', 22i, 20, &c. the quotients of 360', 

 divided by 4, fi. '. 10, 12, 14, 16, 18, &c. we must se- 

 lect any three of these even aliquot parts which make 

 up ISO 3 , as this must be the sum of the angles at which 

 the reflectors are placed. 



v it is obvious that this condition will be complied 

 with, when the angles are 



5=180 



90+60+30=180 

 60+60+60=180 



The polycentral kaleidoscopes are therefore limited 

 to five different forms, viz. 



1. Pour mirrors forming a square, 

 8. Four mirrors forming a rectan 



3. Three mirrors at angles of 90", 4i n , and 



4. Three mirrors at angle* of 90, 60, and SO", and 



5. Three mirrors at angle* of 60*, 60*. and 60. 



SCIT XI. Hiilory of lite Kaleidotcope. 



At this instrument has excited great attention, both 

 in this country and on the continent, we have no doubt 

 tkat our reader* will takr *nme interest in t 

 of the invention. In ate year 1814, when Dr. firew- 

 ater was engaged in experiments on the poUrination of 

 light by succeiaive reflection* between plate* of glass, 

 which were published in the Pkiimojih'ral TV/. 

 lions for 18I'>, nn>l by the Uoyal 



London with Me-hl. the reflector* were in 



-,, n '!- . . ..i.i ,i In c-.uli . )! r. and he had <>cc.i-:iin 

 to remark :r arrangrroent of die images of a 



andle round a centre, or the multiplication of the sec- 

 ton fonm-d by tin- - of the glass plates. In 

 at a subsequent period, the ex]x-riment* of 

 M. Biut on theartinn of fluid-, upon light, Dr. Brew- 

 tcr placed the fluids in a trough furmed by two 

 of glaaa cemented together at an angle. The eye 

 necessarily placed at one end, name of the cement whi 

 had been pressed through twtween the plates appeared 

 * regular figure. The symmetry 

 remarkable. Dr. Drewster set 

 utigate the cause 



'I .'i ilnv LT rli:- lie I|:M >.\ rrr-l tile ie.nl, n_- |i!i::< p!es 



if the KflMtHmmyr 1 1 at, in order to pro- 



' 

 corxutiotis were necessary. 



1. That the reflectors should be placed at an .v 



1 1 wa an even or an od<i 

 when the object was regular, and similar: 

 with respect to both the mirrors; or the etm aliquot 

 ; role when the object was irregular. 



y. That out of an infinite nunilxT of p. -,ti-'ii* for 

 within and without the > 



OL. XII. PART II. 



was only one position where perfect symmetry could 

 be obtained, namely, by placing the object in contact 

 with the ends of the reflector*. 



3. That out of an infinite number of positions for the 

 e\ e, there was only one where the symmetry w-as per- 

 fect, nanielv, as near a.s possible to die angular point, 

 so that the circular field could be distinctly seen ; and 

 that this point was the only one out of an infinite num- 

 ber at which the uniformity of the light of the circular 

 field was a maximum. 



l'|xjn these principles, Dr. Brewster constructed an 

 instrument, in which he fixed permanently across the 

 ends of reflector*, pieces of coloured glass, and other 

 irregular objects, and he shewed the instrument in this 

 state to some members of the linyal Society of Edin- 

 burgh, who were much struck with the beauty of its 

 effects. In this case, however, the forms were nearly 

 permanent, and a .light variation was produced by va- 

 rying the position of the instrument, with respect to 

 the light. The great step, however, towards the com- 

 pletion of the instrument remained yet to lie made, and 

 It was not till some time afterwards that the idea oc- 

 curred to Dr. Brewster of giving motion to ohjecti, such 

 at pieces of coloured glast, $c. trhich trere either Jixed 

 or placed loosely in a cell at the end of' the instrument. 

 When this idea was carried into execution, the kaleido- 

 scope, in its limpleform, was completed. 



In this state, However, the kaleidoscope could not be 

 considered as a general philosophical instrument of uni- 

 versal application; for it was incapable of producing 

 beautiful foniii unless the object was nearly in perfect 

 contact with the end of the reflectors. 



The next, and by far the most tpaftutt *tep of the 

 invention, was therefore to remove this limitation by 

 employing a draw tu!>e and lens, by means of which 

 beautiful forms could be created from objects of all 

 sue*, and at all distances from the observer. In this 

 way the |M>er of the kalei'lnsn.pc ;,- indefinitely c\- 

 I. and every object in nature could be introduced 

 into the picture, in the sajne manner as if thc.-c objects 

 had Ixi n n -.liicttl in size, and actually placed at the 

 end of the reflector*. 



When the instrument was brought to this state of 

 perfection. Dr. Bre%ter was urged by his friends to 

 secure the cxclu.ive property of it by a patent, and he 

 accordingly took out a patent for " a new optical in- 

 strument lor creating and exhibiting beautiful forms." 

 Ill the s| H -cifiiMtion of hn patent, he describes the ka- 

 leidoscope in two different forms. The first consists of 

 two reflecting planes, put together according to the 

 principles already described, and placed in a tube, with 

 an eye-hole in the particular position which gives sym- 

 metry and a maximum uniformity of lit;ht. ami with 

 objects *uch as coloured glass, placed in the position of 

 tymatelry, and put in motion, either hy a rotatory nwte- 

 menl, or by thetr oirn gravity, or by both combated. The 

 second form of the instrument, described in the speci- 

 fication, is, when the tube containing the reflectors i* 

 placed in a second tube, at the end of which is a con- 

 vex lens which introduces iuto the picture objects of al 

 magnitudes, and at every distance, a* baa been already 

 described. 



After the patent WH- -ijjned, and die instruments in 

 a state of forwardness, the gentleman who was em- 

 ! to manufacture them under the patent, carried 

 a kaleidoscope to shew to the principal London optici- 

 ans, for the purpose of taking order-- t'nmi tin in. ' I 



Hen naturi'llv made one for their own u-e. and 

 for the amu'cmei.t of their friends ; and the character 

 3 r 



