edges upon a drawing, will shew it multiplied by repeated reflections. This instrument I have seen in my father's possession 70 years ago, and frequently since, but what has become of it I know not. In my opinion, the application of the principle is very different from that of your kaleidoscope." The following is Professor Playfair's opinion: Edinburgh, 11th May 1818. "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 these contrivances, and from every optical instrument with which I 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 kaleidoscope is a series of figures presented with the most perfect symmetry, so as always to compose a whole, in which nothing 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. optical instruments, should be the means of depriving the Doctor of any part of the reward to which his skill, ingenuity, and perseverance, entitle him so well. JOHN PLAYFAIR, Professor of Natural Philosophy in the University of Edinburgh. "P. S.-Granting that there were a resemblance between the kaleidoany of the particulars mentioned above, scope and Bradley's instrument, in the introduction of coloured and move able objects, at the end of the reflecinstrument. Besides this, a circumtors, is quite peculiar to Dr Brewster's stance highly deserving of attention, is the use of two lenses and a draw tube, so that the action of the kaleidoscope is extended to objects of all sizes, and at all distances from the observer, and united, by that means, to the advantages of the telescope. J. P." Professor Pictet's opinion is stated in the following letter: not been one of the least painfully af"Sir,-Among your friends, I have fected by the shameful invasion of your been a witness of lately in London. Not rights as an inventor, which I have only none of the allegations of the invaders of your patent, grounded on a pretended similarity between your kaleidoscope and Bradley's instrument, or such as Wood's or Harris' theories might have suggested, appear to me to have any real foundation; but, I can affirm that, neither in any of the French, German, or Italian authors, who, to my knowledge, have treated of optics, nor in Professor Charles' justly celebrated and most complete collection of optical instruments at Paris, have I read or seen any thing resembling your ingeniberless applications, and the pleasure ous apparatus, which, from its numit affords, 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. "Next, as to the principle of construction, Dr Brewster's instrument requires a particular position of the eye of the observer, and of the object looked at, in order to its effect. If either of these is wanting, the symmetry vanishes, and the figures are irregular and disunited. In the other two cases, no particular position, cither 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 or vague analogy, between it and other relate, like Professor Wood's, merely M. A. PICTET, Professor of Nat. Phil. in the Academy of Geneva. To Dr Brewster." The propositions in Harris' Option 3 to the multiplication and circular ar- In the 5th scholium he proposes a sort of catoptric box or The reader is requested to examine carefully the propositions in Harris' Optics, which he will find reprinted in the Literary The persons who have pretended to compare Dr Brewster's kaleidoscope with the combinations of plain mirrors described by preceding authors, have not only been utterly 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 examining the construction of the instrument itself. Because it contains two plain mirrors, they infer that it must be the same as every other instrument that contains two plain mirrors; and hence the same persons would, by a similar process of reasoning, have concluded that a telescope is a microscope, or that a pair of spectacles with a double lens is the same as a telescope or a microscope, because all these instruments contain two lenses. An astronomical telescope differs from a compound microscope only in having the lenses placed at different distances. The progress of the rays is exactly the same in both these instruments, and the effect in both is produced by the enlargement of the angle subtended by the object. Yet surely there is no person so senseless as to deny that he who first combined two lenses in such a manner as to discover the mountains of the moon, the satellites of Jupiter and Saturn, and all the wonders of the system of the universe, was the author He who of an original invention. 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 microscope. In the case of the kaleidoscope, the originality of the invention is far more striking. Every person admits that effects are produced by Dr Brewster's intrument, of which no conception could have been previ ously formed. All those who saw it, acknowledged that they had never seen any thing resembling it before; those very persons who had been possessors of Bradley's instrument, who had read Harris's Optics, and made his shew boxes, and who had used other combinations of plain mirrors, never and Journal, No 10. He will then be convinced, that Harris placed both the eye and the object between the mirrors, an arrangement which was known 100 years before his time. supposed for a moment, that the plea- No proof of the originality of the The individuals who have been most eager in this search, did not, perhaps, calculate the degree of mischief which they have done to those who have been led, upon their authority, to encroach upon the rights of others, and thus subject themselves to very serious consequences. The delay which has taken place in commencing legal proceedings, has not arisen from any doubt of the complete originality of the kaleidoscope, and of the defensibility of the patent. As soon as the patentee has made himself acquainted with the circumstance of the individuals who have invaded his patent, with the channels through which they have exported their instruments, and with the amount of the damage which they have done, he will seek for that redress 337 which the law never fails to afford in piracy. We are well assured, that it cases of notorious and unprovoked Dr Brewster to interfere with the never was the intention or the wish of operations of those poor individuals who have gained a livelihood from the manufacture of kaleidoscopes. We know that it will always be a source, of no inconsiderable gratification to him, that he has given employment to thousands of persons, whom the pressure of the times had driven into indigence; and when a decision in favour of his patent is given, as no doubt will be the case, he will never think of enforcing it, excepting against that class of opulent pirates who have been actuated by no other motive but the exorbitant love of gain, in wantonly encroaching upon the property of another. made in London, under Dr Brewster's The patent kaleidoscopes are now sanction, by Messrs P. and G. Dollond, W. and S. Jones, Mr R. B. Bate, Mess. Berge, Mr Thomas Jones, Mr Blunt, Thomas Harris and Son, Mr Bancks, Mr Mr Schmalcalder, Messrs Watkins and Hill, and Mr Smith; in Birmingham by Mr Carpenter; and in Edinburgh by Mr John Ruthven. An account of the different forms in which these ingenious opticians have fitted up the kaleidoscope, and of the new contrivances by which they have given it additional value, will be published in Dr Brewster's Treatise on the Kaleidoscope, now in the press. The public will see, from the examination of these instruments, how much they have been imposed upon by spurious imitations, sold at the most exorbitant prices, and made by individuals entirely ignorant, not only of the principles and construction of the instru ment, but of the method of using it. VOL. III. 2 U LITERARY AND SCIENTIFIC INTELLIGENCE. WE understand that Captain Henry Kater, F. R. S., is appointed by the Board of Longitude to measure the length of the pendulum at Clifton, Leith Fort, and the Shetland Islands, including the stations at which M. Biot measured the length of the pendulum by Borda's apparatus. Captain Kater is well-known to the public, by several ingenious papers in the philosophical transactions, and has shewn himself peculiarly qualified for the present task, by the very fine experiments on the length of the pendulum, which he has recently performed at London. These observations were made by a very ingenious method of his own invention, which is free from almost all the sources of error which affect the French method, and were lately rewarded by the Royal Society of London, with the Copley Medal. Gas Light from Oil.-Mr Taylor of Stratford has completed a very ingenious apparatus, by which gas, for the purposes of illuminstion, may be obtained froni oil. This is a discovery of vast importance for our Greenland fisheries, and is also of great consequence in private houses, as only a very small apparatus is necessary, and there are no disagreeable products as in the distillation of coal. In the gas produced from oil there is more olefiant gas; and when a very fine and pure light is required on particular occasions, wax may be substituted in place of the oil, when almost nothing but olefiant gas is produced. Comet of 1811.-During the course of the last year, M. Schröter, of Lilienthal, has published an account of the comet which appeared in 1811; and by comparing his observations on this comet with those which he made upon that which appeared in 1807, he has been led to form some singular conclusions. The nucleus of the comet of 1811, the apparent diameter of which was 1'49", and which, calculating from the distance, must have had a real diameter of 10,900 miles, M. Schröter supposes to be composed of a fluid covering a solid mass. In the centre of this nucleus we distinguish a second, which is smaller and more luminous, the apparent diameter of which being 16.97", gives a real diameter of 1,697 geographical miles. This central part was surrounded with a particular kind of atmosphere, upon which many of its most remarkable variations depend. Besides this, it was surrounded by a luminous nebulosity, which always exhibited the same brilliancy in every part of its surface, without any appearance of phases; from which circum stance he concludes, that this light, being always equable, cannot be the effect of any reflection of the solar light. Two different parts may be distinguished in the head of this comet : 1. A spherical nebulosity of a whitish coloured light, which surrounded the exterior nucleus, and which is supposed to depend upon the spontaneous luminousness of the body; 2. The posterior part, opposite to the sun, beyond which was extended the double tail; this part was separated from the nucleus by a dark interval, equal to half the total diameter of the head of the comet. The apparent diameter of this head was 34 12", which gives it a real diameter of 2,052,000 geographical miles. The greatest apparent length of the tail is 18°, which gives a real length of 131,852,000 geographical miles. M. Schröter conceives, that we cannot explain this prodigious extent without admitting, that there exists in space around the sun a subtile matter, susceptible of becoming luminous by the combined influence of the sun and the comet. Independent of the force which comets exercise as masses of matter, he conceives that they are endowed with a repulsive and impulsive force, which has some analogy to the electric fluid, and, like it, acts in different directions. Shower of Red Earth in Italy.-In the Annals of Philosophy, for January 1817, there is a short notice of a shower of red earth which fell at Gerace, in Calabria; a late number of the Giornale de Fisica of Brugnatelli, contains a full account of the circumstance, with a description of the substance, by Sig. Sementini, Professor of Chemistry at Naples, of which the following is an extract: It occurred on March 14, 1813: the wind had been westerly for two days, when, at two P. M., it suddenly became calm, the atmosphere became cloudy, and the darkness gradually became so great as to render it necessary to light candles. The sky assumed the colour of red-hot iron, thunder and lightning continued for a considerable length of time, and the sea was heard to roar, although six miles from the city. Large drops of rain then began to fall, which were of a blood-red colour. Sig. Sementini collected a quantity of the powder which fell, and describes its physical properties to be as follows: It had a yellow colour, like canella; an earthy, insipid taste; it was unctuous to the touch, and extremely subtile. When the powder was moderately heated, it changed its co So large a proportion of loss was at first ascribed to some inaccuracy in the analysis, or to some body that had accidently been mixed with the powder; but when he found it always to occur, whatever care was taken in the analysis, he began to suspect that it depended upon some combustible matter essential to the substance. This suspicion was afterwards verified; and by digestion the powder in boiling acohol for a length of time, he obtained from it a greenish yellow colouring matter, which, when dried, acquired a pitchy consistence, was inflammable, and left a carbonaceous residuum. The author remarks, that the existence of chrome in this mineral seems to connect it with the aerolites; but the origin of the combustible substance is very obscure: there were no circumstances connected with the phenomenon which would lead us to suppose that it was of volcanic origin. Supposed Discovery of a Ship near the Cape of Good Hope.-A discovery has been lately made of a quantity of wood in a carbonized state, buried at some depth under the sand, about 10 miles from Cape Town. From the appearance and position of pieces of timber, it has been supposed to consist of the frame-work of a large vessel; and as it is at a considerable distance from the sea, and bears every mark of having been in its present position for a very long period, many speculations have been formed concerning it. The evidence on this point appears, however, to be extremely vague and uncertain; and from the specimens of the wood which have been exhibited in this country, which appear to be in the state of brown coal, as well as from all the circumstances of the case, it is probable that it does not differ from the forests or collections of trees which have been found buried in different situations, in consequence of some of the great revolutions which have formerly occurred on the surface of our globe. Redness of the Sea. The following account of the red colour of the sea on the coast of Africa, near the mouth of the river Loango, is extracted from Professor Smith's journal. Some days ago the sea had a colour as of blood. Some of us supposed it to be owing to the whales, which at this time approach the coasts, in order to bring forth their young. It is, however, a phenomenon which is generally known, has often been described, and is owing to myriads of infused animalculæ. I examined some of them taken in this blood-coloured water; when highly magnified, they do not appear larger than the head of a small pin. They were at first in rapid motion, which, however, soon ceased, and at the same instant the whole animal separated into a number of spherical particles." New Extracts from Coal.-Dr Jassmeyer, Professor of Chemistry in Vienna, has discovered the means of extracting from coals two hitherto unknown acids, a resin, a resinous gum, and other elements, which he has employed with surprising success to the purposes of dyeing wool, silk, hair, and linen, and has produced from them red, black, yellow, and various shades of brown and gray. Count Von Chorinsky, Presi dent of the Aulic Chamber, and many other enlightened judges of these matters, were present at these experiments, and testified their entire approbation of this useful discovery. Locusts in India.-About the 20th June 1812, a very large flight of locusts was observed hovering about Etawah, which at length settled in the fields east of the town, where they remained some time, and were seen copulating in vast numbers; they then took their departure, but continued to hover about the place for a month afterwards. On the 18th of July, while riding in that direction, I discovered a tremendous swarm of very small dark-coloured insects in the vicinity of a large pool of stagnant water; they were collected in heaps, and covered the ground to a considerable distance. These, on minute inspection, proved to be locusts in miniature, but without wings. In this place they remained, hourly increasing in numbers, for some days, when the great body moved off, taking a direction towards the town of Etawah: they crept and hopped along at a slow rate, until they reached the town, where they divided into different bodies, still however keeping nearly the same direction, covering and destroying every thing green in their progress, and distributing themselves all over the neighbourhood. The devastation daily committed by them being almost incalculable, the farmers were under the necessity of collecting as many people as they could, in the vain hope that they might preserve the crop by sweeping the swarm backwards; but as often as they succeeded in repelling them in one quarter, they approached in another: fires were then lighted all round the fields with the same view ;-this had the effect of keep |