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edges upon a drawing, will shew it optical instruments, should be the multiplied by repeated reflections. This means of depriving the Doctor of any instrument I have seen in my father's part of the reward to which his skill
, possession 70 years ago, and frequent- ingenuity, and perseverance, entitle ly since, but what has become of it I him so well. know not. In my opinion, the appli
John PLAYFAIR, cation of the principle is very different Professor of Natural Philosophy in from that of your kaleidoscope.”
the University of Edinburgh. The following is Professor Playfair's
“ P. S.-Granting that there were opinion :
a resemblance between the kaleidoEdinburgh, 11th May 1818. “ I have examined the kaleidoscope
scope and Bradley's instrument, in invented by Dr Brewster, and com
any of the particulars mentioned above,
the introduction of coloured and movepared it with the description of an in- able objects, at the end of the reflecstrument which it has been said to resemble, constructed by Bradley in
tors, is quite peculiar to Dr Brewster's
instrument. Besides this, a circum1717. I have also compared its effect with an experiment to which it may
stance highly deserving of attention,
is the use of two lenses and a draw be thought to have some analogy, des
tube, so that the action of the kaleidocribed by Mr Wood in his optics,
scope is extended to objects of all Prop. 13 and 14. “From both these contrivances, and sizes, and at all distances from the
observer, and united, by that means, from every optical instrument with which I am acquainted, the kaleido- to the advantages of the telescope.
J. P.” scope appears to differ essentially both in its effect and in the principles of its Professor Pictet's opinion is stated construction.
in the following letter : “ As to the effect, the thing produced by the kaleidoscope is a series
“Sir,- Among your friends, I have of figures presented with the most per
not been one of the least paintully af
fected by the shameful invasion of your fect symmetry, so as always to compose a whole, in which nothing is rights as an inventor, which I have
been a witness of lately in London. Not wanting and nothing redundant. It matters not what the object be to only none of the allegations of the inwhich the instrument is directed, if it vaders of your patent, grounded on only be in its proper place the effect
a pretended similarity between your just described is sure to take place,
kaleidoscope and Bradley's instruand with an endless variety. In this
ment, or such as Wood's or Harris' respect, the kaleidoscope appears to be
theories might have suggested, appear quite singular among optical instru
to me to have any real foundation ; ments. Neither the instrument of but, I can affirm that, neither in any Bradley, nor the experiment or theorem of the French, German, or Italian in Wood's book, have
authors, who, to my knowledge, have resemblance
any to this ; they go no further than the treated of optics, nor in Professor multiplication of the figure.
Charles' justly celebrated and most “ Next, as to the principle of con
complete collection of optical instrustruction, Dr Brewster's instrument
ments at Paris, have I read or seen requires a particular position of the any thing resembling your ingenieye of the observer, and of the object berless applications, and the pleasure
ous apparatus, which, from its numlooked at, in order to its effect. If ei- it affords, and will continue to afford, ther of these is wanting, the symme
to millions of beholders of its matchtry vanishes, and the figures are irre
less effects, may be ranked among
the gular and disunited. In the other two cases, no particular position, either most happy inventions science ever for the eye or the object, is required.
presented to the lovers of rational en“For these reasons, Dr Brewster's joyment.
M. A. PICTET, invention seems to me quite unlike the other two. Indeed, as far as I
Professor of Nat. Phil. in the
Academy of Geneva. know, it is quite singular among opti- To Dr Brewster.” cal instruments; and it will be matter of sincere regret, if any imaginary
The propositions in Harris' Optics or vague analogy, between it and other relate, like Professor Wood's, merely
to the multiplication and circular ar- The persons who have pretended to rangement of the apertures or sectors compare Dr Brewster's kaleidoscope formed by the inclined mirrors, and with the combinations of plain mir. to the progress of a ray of light reflect- rors described by preceding authors, ed between two inclined or parallel have not only been utterly unacquaintmirrors; and no allusion whatever is ed with the principles of optics, but made, in the propositions themselves, have not been at the trouble either of to any instrument. In the proposi- understanding the principles on which tion respecting the multiplication of the patent kaleidoscope is constructed, the sectors, the eye of the observer is or of examining the construction of never once mentioned, and the pro- the instrument itself. Because it conposition is true if the eye has an infi- tains two plain mirrors, they infer that nite number of positions; whereas, it must be the same as every other inin the kaleidoscope, the eye can only strument that contains two plain mirhave one position. In the other propo- rors; and hence the same persons would, sition, (Prop. XVII.) respecting the by a similar process of reasoning, have progress of the rays, the eye and the concluded that a telescope is a microobject are actually stated to be placed be- scope, or that a pair of spectacles with tween the reflectors; and even if the eye a double lens is the same as a telehad been placed without the reflectors, scope or a microscope, because all
a as in the kaleidoscope, the position these instruments contain two lenses. assigned it, at a great distance from An astronomical telescope differs from the angular point, is a demonstra- a compound microscope only in having tion that Harris was entirely ignore the lenses placed at different distances. ant of the positions of symmetry ei- The progress of the rays is exactly the ther for the object or the eye, and same in both these instruments, and could not have combined two reflectors the effect in both is produced by the so as to form a kaleidoscope for pro- enlargement of the angle subtended ducing beautiful or symmetrical forms. by the object. Yet surely there is no The only practical part of Harris's pro- person so senseless as to deny that he positions is the 5th and 6th scholia to who first combined two lenses in such Prop. XVII.
In the 5th scholium a manner as to discover the mountains he proposes a sort of catoptric box or of the moon, the satellites of Jupiter cistula, known long before his time, and Saturn, and all the wonders of the composed of four mirrors, arranged in system of the universe, was the author a most unscientific manner, and con- of an original invention. He who taining opaque objects between the spe- produces effects which were never proculums. “Whatever they are,” says duced before, even by means which he, when speaking of the objects, have been long known, is unquestions “the upright figures between the ably an original inventor ; and upon speculums should be slender, and not this principle alone can the telescope too many in number, otherwise they be considered as an invention different will too much obstruct the reflected from the microscope. In the case of rays from coming to the eye." This the kaleidoscope, the originality of the shews, in a most decisive manner, that invention is far more striking. Every Harris knew nothing of the kaleido- person admits that effects are produced scope, and that he has not even im- by Dr Brewster's intrument, of which proved the common catoptric cistula, no conception could have been previwhich had been known long before. ously forined. All those who saw it, The principle of inversion, and the acknowledged that they had never seen positions of symmetry, were entirely any thing resembling it before; and unknown to him. In the 6th scho- those very persons who had been poslum, he speaks of rooms lined with sessors of Bradley's instrument, who looking-glasses, and of luminous am- had read Harris's Optics, and made phitheatres, which, as the Editor of his shew boxes, and who had used other the Literary Journal observes, have combinations of plain mirrors, never been described and figured by all the old writers on optics. *
Journal, No 10. He will then be convin
ced, that Harris placed both the eye and . The reader is requested to examine the object between the mirrors, an arrangecarefully the propositions in Harris' Optics, ment which was known 100 years before which he will find reprinted in the Literary his time.
supposed for a moment, that the plea- which the law never fails to afford in sure which they derived from the ka- cases of notorious and unprovoked leidoscope had any relation to the ef- piracy. We are well assured, that it fects described by these authors. never was the intention or the wish of
No proof of the originality of the Dr Brewster to interfere with the kaleidoscope could be stronger than the operations of those poor individuals sensation which it excited in London who have gained a livelihood from and Paris. In the memory of man, the manufacture of kaleidoscopes. We no invention, and no work, whether know that it will always be a source, addressed to the imagination or to the of no inconsiderable gratification to understanding, ever produced such an him, that he has given employment effect. A universal mania for the in- to thousands of persons, whom the strument seized all classes, from the pressure of the times had driven into lowest to the highest, from the most indigence; and when a decision in fa. ignorant to the most learned, and vour of his patent is given, as no doubt every person not only felt, but ex- will be the case, he will never think of pressed the feeling, that a new plea- enforcing it, excepting against that class sure had been added to their existence. of opulent pirates who have been actua
If such an instrument had ever been ated by no other motive but the exorknown before, a similar sensation must bitant love of gain, in wantonly enhave been excited, and it would not croaching upon the property of another. have been left to the ingenuity of The patent kaleidoscopes are now the half learned and the half honest made in London, under Dr Brewster's to search for the skeleton of the in- sanction, by Messrs P. and G. Dollond, vention among the rubbish of the 16th W. and S. Jones, Mr R. B. Bate, Mess. and 17th centuries.
Thomas Harris and Son, Mr Bancks, Mr The individuals who have been most Berge, Mr Thomas Jones, Mr Blunt, eager in this search, did not, perhaps, Mr Schmalcalder, Messrs Watkins calculate the degree of mischief which and Hill, and Mr Smith; in Birmingthey have done to those who have been ham by Mr Carpenter; and in Edinled, upon their authority, to encroach burgh by Mr John Ruthven. An acupon the rights of others, and thus sub- count of the different forms in which ject themselves to very serious conse- these ingenious opticians have fitted up quences. The delay which has taken the kaleidoscope, and of the new con place in commencing legal proceedings, trivances by which they have given it has not arisen from any doubt of the additional value, will be published in complete originality of the kaleidoscope, Dr Brewster's Treatise on the Kaleidosand of the defensibility of the patent. Cope, now in the press. The public As soon as the patentee has made will see, from the examination of these himself acquainted with the circum- instruments, how much they have stance of the individuals who have been imposed upon by spurious imiinvaded his patent, with the channels tations, sold at the most exorbitant through which they have exported prices, and made by individuals entheir instruments, and with the a- tirely ignorant, not only of the prinmount of the damage which they have ciples and construction of the instru. done, he will seek for that redress ment, but of the method of using it.
LITERARY AND SCIENTIFIC INTELLIGENCE.
We understand that Captain Henry Kater, stance he concludes, that this light, being F. R. S., is appointed by the Board of Lon- always equable, cannot be the effect of any gitude to measure the length of the pendu- reflection of the solar light. lum at Clifton, Leith Fort, and the Shet. Two different parts may be distinguished land Islands, including the stations at which in the head of this comet : 1. A spherical M. Biot measured the length of the pendu- nebulosity of a whitish coloured light, lum by Borda's apparatus. Captain Kater which surrounded the exterior nucleus, and is well-known to the public, by several in which is supposed to depend upon the
spongenious papers in the philosophical trans- taneous luminousness of the body ; 2. The actions, and has shewn himself peculiarly posterior part, opposite to the sun, beyond qualified for the present task, by the very which was extended the double tail; this fine experiments on the length of the pen- part was separated from the nucleus by a dulum, which he has recently performed at dark interval, equal to half the total diameLondon. These observations were made by ter of the head of the comet. a very ingenious method of his own inven. rent diameter of this head was 34 12", tion, which is free from almost all the which gives it a real diameter of 2,052,000 sources of error which affect the French geographical miles. method, and were lately rewarded by the The greatest apparent length of the Royal Society of London, with the Copley tail is 18°, which gives a real length of Medal.
131,852,000 geographical miles. M. SchröGas Light from Oil.-Mr Taylor of ter conceives, that we cannot explain this Stratford has completed a very ingenious prodigious extent without admitting, that apparatus, by which gas, for the purposes there exists in space around the sun a subof illumination, may be obtained from oil. tile matter, susceptible of becoming lumi. This is a discovery of vast importance for nous by the combined influence of the sun our Greenland fisheries, and is also of great and the comet. Independent of the force consequence in private houses, as only a very which comets exercise as masses of matter, small apparatus is necessary, and there are he conceives that they are endowed with a no disagreeable products as in the distilla- repulsive and impulsive force, which has tion of coal. In the gas produced from oil some analogy to the electric fluid, and, like there is more olefiant gas ; and when a very it, acts in different directions. fine and pure light is required on particular Shower of Red Earth in Italy. In the occasions, wax may be substituted in place Annals of Philosopby, for January 1817, of the oil, when almost nothing but olefiant there is a short notice of a shower of red gas is produced.
earth which fell at Gerace, in Calabria ; a Comet of 1811.—During the course of the late number of the Giornale de Fisica of last year, M. Schröter, of Lilienthal, has Bragnatelli, contains a full account of the published an account of the comet which ap- circumstance, with a description of the subpeared in 1811; and by comparing his ob. stance, by Sig. Sementini, Professor of Cheservations on this comet with those which mistry at Naples, of which the following he made upon that which appeared in 1807, is an extract : he has been led to form some singular con- It occurred on March 14, 1813: the clusions. The nucleus of the comet of wind had been westerly for two days, when, 1811, the apparent diameter of which was at two P. M., it suddenly became calm, the 1' 49', and which, calculating from the dis- atmosphere became cloudy, and the dark tance, must have had a real diameter of
ness gradually became so great as to render 10,900 miles, M. Schröter supposes to be it necessary to light candles. The sky ascomposed of a fluid covering a solid mass. sumed the colour of red-hot iron, thunder In the centre of this nucleus we distinguish and lightning continued for a considerable a second, which is smaller and more lumi. length of time, and the sea was heard to nous, the apparent diameter of which being roar, although six miles from the city. 16.97", gives a real diameter of 1,697 geo- Large drops of rain then began to faú, graphical miles. This central part was sur- which were of a blood-red colour. rounded with a particular kind of atmos- Sig. Sementini collected a quantity of the phere, upon which many of its most re- powder which fell, and describes its physi. inarkable variations depend. Besides this, cal properties to be as follows: It had a it was surrounded by a luminous nebulosity, yellow colour, like canella ; an earthy, inwhich always exhibited the same brilliancy sipid taste ; it was unctuous to the touch, in every part of its surface, without any ap- and extremely subtile. When the powder pearance of phases ; from which circum- was moderately heated, it changed its co
lour, first to a brown, and afterwards to a Loango, is extracted from Professor Smith's black, and became red again as the tempe. journal. rature was raised ; after it had been heat- Some days ago the sea had a colour as of ed, many small shining plates were visible, blood. Some of us supposed it to be owing it no longer effervesced with acids, and had to the whales, which at this time approach Lost about one-tenth of its weight. Its spe- the coasts, in order to bring forth their cific gravity was 2.07.
young. It is, however, a phenomenon Sig. Sementini then subjected the powder which is generally known, has often been to chemical analysis, and found its compo. described, and is owing to myriads of insition to be as follows:
fused animalculæ. I examined some of them
taken in this blood-coloured water; when Silex.........
highly magnified, they do not appear larger Alumine
than the head of a small pin. They were Lime
at first in rapid motion, which, however, Chrome
soon ceased, and at the same instant the Iron.......
whole animal separated into a number of Carbonic acid
New Extracts from Coal.-Dr Jassmeyer,
Professor of Chemistry in Vienna, has dis100
covered the means of extracting from coals So large a proportion of loss was at first two hitherto unknown acids, a resin, a ascribed to some inaccuracy in the analysis, resinous gum, and other elements, which or to some body that had accidently been he has employed with surprising success to mixed with the powder ; but when he found the purposes of dyeing wool, silk, hair, and it always to occur, whatever care was taken linen, and has produced from them red, in the analysis, he began to suspect that it black, yellow, and various shades of brown depended upon some combustible matter and gray. Count Von Chorinsky, Presiessential to the substance. This suspicion dent of the Aulic Chamber, and many other was afterwards verified ; and by digestion enlightened judges of these matters, were the powder in boiling acohol for a length of present at these experiments, and testified time, he obtained from it a greenish yellow their entire approbation of this useful dis. colouring matter, which, when dried, ac- covery. quired a pitchy consistence, was inflam- Locusts in India.About the 20th June mable, and left a carbonaceous residuum. 1812, a very large flight of locusts was obThe author remarks, that the existence of served hovering about Etawah, which at chrome in this mineral seems to connect it length settled in the fields east of the town, with the aerolites; but the origin of the com- where they remained some time, and were bustible substance is very obscure: there seen copulating in vast numbers; they then were no circumstances connected with the took their departure, but continued to hover phenomenon which would lead us to sup- about the place for a month afterwards. pose that it was of volcanic origin.
On the 18th of July, while riding in that Supposed Discovery of a ship near the direction, I discovered a tremendous swarm Cape of Good Hope. A discovery has been of very small dark-coloured insects in the lately made of a quantity of wood in a car. vicinity of a large pool of stagnant water; bonized state, buried at some depth under they were collected in heaps, and covered the sand, about 10 miles from Cape Town. the ground to a considerable distance. From the appearance and position of pieces These, on minute inspection, proved to be of timber, it has been supposed to consist of locusts in miniature, but without wings. In the frame-work of a large vessel ; and as it this place they remained, hourly increasing is at a considerable distance from the sea, in numbers, for some days, when the great and bears every mark of having been in its body moved off, taking a direction towards present position for a very long period, the town of Etawah: they crept and hopped many speculations have been formed con- along at a slow rate, until they reached the cerning it. The evidence on this point ap- town, where they divided into different bopears, however, to be extremely vague and dies, still however keeping nearly the same uncertain ; and from the specimens of the direction, covering and destroying every wood which have been exhibited in this thing green in their progress, and districountry, which appear to be in the state of buting themselves aự over the neighbourbrown coal, as well as from all the circum- hood. The devastation daily committed by stances of the case, it is probable that it does them being almost incalculable, the farmers not differ from the forests or collections of were under the necessity of collecting as trees which have been found buried in dif- many people as they could, in the vain hope ferent situations, in consequence of some of that they might preserve the crop by sweepthe great revolutions which have formerlying the swarm backwards ; but as often as occurred on the surface of our globe. they succeeded in repelling them in one
Redness of the Sea. The following ac- quarter, they approached in another : fires ,count of the red colour of the sea on the were then lighted all round the fields with coast of Africa, near the mouth of the five the same view ;-this had the effect of keep