" It has been said here," says Mr. Watt, " that you took the idea of the kaleidoscope from an old book on garden ing. My friend, the Rev. Mr. Corrie, has procured me a sight of the book. It is Bradley's Improvements of Plant ing and Gardening. London 1731, part 2d. chap. 1st. it consists of two pieces of looking glass of equal bigness, of the figure of a long square, five inches long and four inches high, hinged together, upon one of the narrow sides, so as to open and shut like the leaves of a book, which, being set upon their edges upon a drawing, will show it multi plied by repeated reflections, This instrument I have seen in my father's possession 70 years ago, and frequent ly since, but what has become of it I know not. In my ers of your patent, grounded on a pretended similarity be tween your kaleidoscope and BradlLy's instrument, or such as Wood's or Harris' theories might have suggested, ap pear to me to have any real foundation ; but I can affirm, that, neither in any of the French, German, or Italian au thors, who, to my knowledge, have treated of optics, nor in Professor Charles' justly celebrated and most complete col lection of optical instruments at Paris, have I read or sect, any thing resembling your ingenious apparatus, which, from its numberless applications, and the pleasure it af fords, and will continue to afford, to millions of beholders of its matchless effects, may be ranked among the most • happy inventions science ever presented to the lovers of rational enjoyment.
opinion, the application of the principle is very different from that of your kaleidoscope " The following is Professor Play fait's opinion : Edinburgh, I 1 th May, I 818.
" I have examined the kaleidoscope invented by Dr. Brewster, and compared it with the description of an in strument which it has been said to resemble, constructed by Bradley in 1717. I have also compared its effect • with an experiment to which it may be thought to have some analogy, described by Mr. Wood in his Optics, Prop. 13 and 14.
" From both thesc contrivances, and from every optical instrument with which 1 am acquainted, the kaleidoscope appears to differ essentially, both in its effect and in the principles of its construction.
" As to the effect, the thing produced by the kaleido scope is a seriesof figures presented with the most perfect symmetry, so as always to compose a whole, in which no thing is wanting and nothing redundant. It matters not what the object be to which the instrument is directed, if it only be in its proper place, the effect just described is sure to take place, and with an endless variety. In this respect, the kaleidoscope appears to be quite singular among optical instruments. Neither the instrument of Bradley, nor the experiment or theorem in Wood's book, have any resemblance to this ; they go no further than the multiplication of the figure.
" Next, as to the principle of construction, Dr. Brew ster's instrument requires aparticu/ar position of the eye of the observer, and of the object looked at, in order to its ef fect. If either of these is wanting, the symmetry vanishes, and the figures are irregular and disunited. In the other two cases, no particular position, either for the eye or the object, is required.
" For these reasons, Dr. Brewster's invention seems to me quite unlike the other two. Indeed, as far as I know,it is quite singular among optical instruments ; and it will be matter of sincere regret, if any imaginary oe vague ana logy, between it and other optical instruments, should be the means of depriving the Doctor of any part of the re ward to which his skill, ingenuity, and perseverance, enti tle him so well.
" P. S.—Granting that there were a resemblance be tween the kaleidoscope and Bradley's instrument, in any of the particulars mentioned above, the introduction of co loured and moveable objects, at the end of the reflectors, is quite peculiar to Dr. Brewstet's instrument. Besides this, a circumstance highly deserving of attention, is the use of two lenses and a draw tube, so that the action of the kalei doscope is extended to objects of all sizes, and at all dis tances from the observer, and united, by that means, to the advantages of the telescope.
Professor Pictet's opinion is stated in the following let ter : StR,—Among your friends, I have not been one of the least painfully affected by the shameful invasion of your rights as an inventor, which I have been a witness of lately in London. Not only none of the allegations of the invad The propositions in Harris' Optics relate, like Professor Wood's, merely to the multiplication and circular arrange ment of the apertures or sectors formed by the inclined mirrors, and to the progress of a ray of light reflected be tween two inclined or parallel mirrors; and no allusion whatever is made, in the propositions themselves, to any in strument. In the proposition respecting the multiplica tion of the sectors, the eye of the observer is never once mentioned, and the proposition is true, if the eye has an in finite number of positions ; whereas, in the kaleidoscope, the eye can only have one position. In the other proposi tion, (Prop. XVII.) respecting the progress of the rays, the eye and the object are actually stated to be placed be tween the reflectors ; and even if the eye had been placed without the reflectors, as in the kaleidoscope, the position assigned it, at a great distance from the angular point, is a demonstration that Harris was entirely ignorant of the posi tions of symmetry either for the object or the eye, and could not have combined two reflectors so as to form a kaleido scope for producing beautiful or symmetrical forms. The
only practical part of Harris' propositions is the 5th and 6th scholia to Prop. XVII. In the 5th scholium he pro poses a sort of catoptlic box or cistula, known long before his time, composed of four mit rors, arranged in a most un scientific manner, and containing opaque objects between the speculums. " Whatever they are," says he, when speaking of the objects, " the upright figures between the speculums should be slender, and not too many in num ber, otherwise they will too much obstruct the reflected rays from coming to the eye " This sheivs, in a most deci sive manner, that Harris knew nothing of the kaleidos cope, and that he has not even improved the common ca toptric cistula, which had been known long before. The principle of inversion, and the positions of symmetry, were entirely unknown to him. In the 6th scholium, he speaks of rooms lined with looking-glasses, and of luminous am phitheatres, which have been described and figured by all the old writers on optics.* The persons who have pretended to compare Dr. Brew ster's kaleidoscope with the combinations of plain mirrors described by preceding authors, have not only been utter ly unacquainted with the principles of optics, but have not been at the trouble either of understanding the principles on which the patent kaleidoscope is constructed, or of ex amining the construction of the instrument itself. Be cause it contains two plain mirrors, they infer that it must be the same as every other instrument that contains two plain mirrui s, and hence the same persons would, by a si ' milar process of reasoning, have concluded that a tele scope is a microscope, or that a pair of spectacles with a double lens is the same as a telescope or a mid °scope, because all these mstrumottts contain two lenses. An as tronomical telescope differs ft um a compound mieloscope only in having the krises placed at different distances. The progress of the rat s is exactly the same in both these instruments, and the effect in both is produced by the en largement of the angle subtended by the object. Yet sure ly there is no person SD senseless, as to deny that he who first combined two lenses in such a manner as to discover the mountains oldie MOOD, the satellites of Jupiter and Sa turn, and all the wonders of the system of the universe, was the author of an original invention lie who produces effects which were never produced before, even by means which have been long known, is unquestionably an original inventor ; and upon this principle alone can the telescope be considered as an invention different from the micros cope. In the case of the kaleidoscope, the originality of the invention is far mote striking. Every pct son admits that effects are produced by Dr. Brew ster's instrument, of which no conception could have been previously formed. All those who saw it, acknowledged that they had never seen any thing it before ; and those very per sons who had been possessors of Bradley's instrument, who had read Harris' Optics, and made his spew boxes, and who had used other combinations of plain mirrors, never supposed for a moment, that the pleasure which they had derived from the kaleidoscope had any relation to the effects described by these authors.
No proof of the originality of the kaleidoscope could be stronger than the sensation which it excited in London and Paris. In the memory of no invention, and no work, whether addressed to the imagination or to the understand ing, ever produced such an effect. A universal mania for the instrument seized all classes, from the lowest to the highest, from the most ignorant to the most learned, and every person not only felt, but expressed the feeling, that a new pleasure had been added to their existence.
If such an instrument had ever been known before, a si milar sensation must have been excited, and it would not have been left to the ingenuity of the hall learned and the half honest, to search fur the skeleton of the invention among the rubbish of the 16th and 17th centuries.
The patent kaleidoscopes are now made in London, un der the sanction of the Patentee, by Messrs. P. and G. Dol lond, W. and S. Jones, Mr. B. B. Bate, Messrs. Thomas Harris and Son, Messrs. W. and T. Gilbert, Mr. Bancks, Mr. Berge, Mr. Thomas Jones, Mr. Blunt, Mr. Schmal calder, Messrs. Watkins and Hill, and Mr. Smith. In Birmingham by Mr. Philip Carpenter ; in Bristol by Mr. Beilby ; and in Edinburgh by Mr. John Ruthven. An ac count of the different forms in which these ingenious opti cians have fitted up the kaleidoscope, and of the new con trivances by which they have given it additional value, will he published in Dr. Brewster's Treatise on the Kaleido scope, now in the press.