C A L 



■,\ hilft the artift is engaged in copying it. It is alfo capahle 

 of being ufed with Dr. Wollallon's camera hicida, by 

 which means thofe who would otherwife be \mable to 

 copy the patterns may do it with perfeA facihty and 

 accuracy. The effects of the inftrument may alfo be exhi- 

 bited to many perfons at once, on the principles of the 

 folar microfcope, or magic lantern. The inftrument for 

 fcientific purpofes is occafionally fo conftrucled as to admit 

 of the inclination of the refleftors being varied at pleafure. 

 Under the authority of Dr. Brewfter, caleidofcopes of all 

 the different forms are manufaftured by the opticians with 

 great accuracy and perfeftion ; but the popularity of the 

 inftrument has been fuch as to induce a great number of 

 individuals, who have been ignorant of its principles, to 

 infringe upon the patent, and impofe upon the public a 

 wretched imitation of the original, poffefling none of the 

 properties which are effentially neceffary to the prodiiftion 

 of beautiful and fymmetrical forms ; and in order to juftify 

 fuch proceedings, it became neceffary to fearch out for fome 

 combination of mirrors already defcribed, which might have 

 fome refemblance to Dr. Brewfter's inftrument : and the 

 firft fuppofed anticipation of it was found in prop. 13 and 

 14 of Wood's Optics ; but profeffor Wood, in a letter to 

 Dr. Brewfter on the fubjeft, has moft handfomely difclaimed 

 having in contemplation the effefts produced by the caleido- 

 fcope in giving the propolitions alluded to. The next fup- 

 pofed anticipation was an inftrument propofed and made 

 by Mr. Bradley in 1 71 7, which confifted of two pieces of 

 iilvered looking-glafs, five inches wide, and four inches 

 high, jointed together with hinges, and opening like a 

 book. Thefe plates being fet upon a geometrical drawing, 

 and the eye being placed in front of the mirrors, the lines 

 of the drawing were feen multiplied by repeated reflections. 

 This inftrument had been defcribed long before by Kircher, 

 and did not receive a fingle improvement from the hands of 

 Bradley. It had been often made by the opticians ; but 

 no perfbn ever thought of applying it to any purpofe of 

 utility, or of uflng it as an inftrument of rational amufement 

 by the creation of beautiful forms : indeed, from its con- 

 ilruction, it is quite incapable of producing any of the 

 imgular effefts of the caleidofcope. As, however, the 

 fimilarity between the two inftruments is maintained by 

 many perfons, either from ignorance or interefl ; in order, 

 therefore, to render that juftice to Dr. Brewfter which 

 to us appears his due, we give the following ftateraent of 

 the differences between the two inftruments, upon the fup- 

 pofition of their both being applied to geometric lines upon 

 paper. 



C A L 



1. In Bradley's inftru- 

 ment, the length is lefs than 

 the breadth of the plates. 



2. Bradley's inftrument 

 cannot be ufed with a tube. 



3. In Bradley's inftru- 

 ment, from the erroneous 

 pofition of the eye, there is 

 a great inequahty of light in 

 the feftors, and the Laft fec- 

 tors are fcarcely vifible. 



4. In Bradley's inftru- 

 ment, the figure confifts of 

 elliptical, and confequently 

 unequal feftors. 



1 . In the caleidofcope, the 

 length of the plates muft be 

 four, five, or fix times their 

 breadth. 



2. The caleidofcope can- 

 not be ufed without a tube. 



3. In the caleidofcope, the 

 eye is fo placed, that the 

 uniformity of light is a maxi- 

 mum, and the laft feftors are 

 diftinftly vifible. 



4. In the caleidofcope, all 

 the feftors are equal, and 

 compofe a perfect circle, and 

 the picture is perfectly fym- 

 metrical. 



5. In Bradley's inftru- 

 ment, the unequal feftors do 

 not unite, but are all fepa- 

 rated from one another by a 

 fpace equal to the thicknefs 

 of the mirror-glafs. 



6. In Bradley's inftru- 

 ment, tlie images reflected 

 from the firft furface inter- 

 fere wit"h thofe reflefted from 

 the fecond, and produce a 

 confufion and overlapping of 

 images entirely inconfiftent 

 with fymmetry. 



7. In Bradley's inftru- 

 ment, the defcfts in the 

 junction of the plates are all 

 rendered vifible by the erro- 

 neous pofition of the eye. 



5. In the caleidofcope, the 

 equal feCtors ail unite into 

 a complete and perfeftly fym- 

 metrical form. 



6. In the caleidofcope, the 

 fecondary refieftions are en- 

 tirely removed, and therefore 

 no confufion takes place. 



7. In the caleidofcope, the 

 eye is fo placed, that thefe 

 defects of junction are invi- 

 fible. 



To which it may be added, that profeffors Playfair of 

 Edinburgh, and PiCtet of Geneva, and the celebrated Mr. 

 Watt, have each of them borne teftimony to the difiimilarity 

 of the two inftruments, and to the unqueftionable claim 

 which Dr. Brewfter has to the invention of the caleidofcope. 



CALENDAR. To the French calendar, aimex — the 

 French have aboliflied their new calendar, and reftored the 

 Gregorian, which was ordered to be ufed in all their dates 

 after the ift of January, 1806. 



CALEYA, in Botany, a very diftinfl and elegant genus, 

 thus named by Mr. Brown, in juft commemoration of Mr. 

 George Caley, an able and accurate botanift, who has for 

 feveral years been employed by fir Jofeph Banks, in tfie 

 inveftigation of the vegetable productions of New South 

 Wales, but whofe difcoveries are not all admitted into Mr. 

 Brown's work, being, we hope, deflmed to appear in fome 

 more popular, and more amply defcriptivc, publication. — 

 Brown in Ait. Hort. Kew. v. 5. 204. (Caleana; Br. Prodr. 

 Nov. Holl. V. I. 329.) — Clafs and order, Gynandria Monan- 

 dr'ta. Nat. Ord. Orchidea. 



Eff. Ch. Flower reverfed. Calyx-leaves and petals linear, 

 nearly equal, fpreading. Lip ftalked, peltate, hollow, 

 opening outwards. Style dilated. Anther a permanent 

 lid. Pollen powdery. 



There are two fpecies, C. major and minor, both found 

 near Port Jackfon ; the former fent to Kew, by Mr. Caley, 

 in 1810. Thefe are {mool\iherbs, with fimple naked bulbs. 

 Leaf radical, folitary, hnear, fheathed at the bafe. Flowers 

 few, brownifh-green ; the Up and column red. The Up is 

 moveable, reflexed ; but during rain it becomes inflexed over 

 the column, which Mr. Brown is doubtful whether to attri- 

 bute to the diminution of light, or to the irritation of the 

 rain. 



CALICIUM, from xa'A-jKm; a Utile cup, well ex- 

 prefGng the form of the fruftification — Perf. in Uft. Ann. 

 fafc. 7. 20. Achar. Syn. 55. " Lichenogr. 39. t. 3. f. i — 

 8." — Clafs and order, Cryptogamia Alg<e. Nat. Ord. 

 L'tchencs. 



Efl". Ch. Cruft uninterrupted, uniform. Receptacles cup- 

 fhaped, cartilaginous, ftalked, more or lefs elevated, con- 

 taining a compadt powdery mafs of feeds, forming an even 

 diflt. ■ . ■ 



Acharius defines twenty-five fpecies of this curious and 

 beautiful, tliough minute and inconfpicuous genus of the 

 Lichen tribe. They form grey, white, or yellow patches, of 

 various extent, on old wrought wood, or boards, expofed to 



the 



