m 



CYCLOPEDIA. 



CYMOLK. 



S7B 



circular area c i- M, and the whole am A c B Is three times that of the 

 generating circle. 



5. The curvature at 4 is the same u that in a circle whose radius u 

 twice I r, and the involute and erolute <*ee theM terms) of * cycloid 

 are both cycloid* of the Mine magnitude. 



6. If the figure be ravened, K> that c U the lowest point of the 

 cycloid, and A and the highest poiuU; then, no f notion being 

 supposed, and the cycloid being of resisting matter, a small weight 

 placed at 4 will take the aune time to alide to c, whatever the point 4 

 may be. Hence all the arc* of the cycloid are aaid to be MMMMM 



6. On the same (uppoaiUon u in the preceding, a weight will slide 

 from B to 4 in a ahorter time than in any other curve which can be 

 drawn between B and 4. Hence the cycloid ia called the tirarhi/tlvdiro*. 



Let be the angle COP (in theoretical unite) [ANGLE], cx=x, 

 M y = y, o F = a, then we have the following equations : 

 *=o(l-coe; 



from which the propbrtiea of the curve may be deduced. 



If, instead of measuring rq from r, we had carried it forward from 

 M, then 4 would have described a curve known by the name of the 

 nmfxmiuH to the cycloid, but which is in truth a curve o/nno. [SmE8, 

 CURVE or.] 



The history of the cycloid is remarkable from the contests which it 

 produced, and the manner in which the names of Galileo, Descartes, 

 Mersenne, Pascal, Roberval, Wallis, and others, appear in connection 

 with it. But there would be little use hi giving an abstract of history 

 on points of no material use, and the interest of which depends on the 

 light in which a detailed account, and nothing less, would place the 

 state of science of the 17th century. Galileo was certainly the first 

 who attempted the investigation of the properties of the cycloid, as 

 appears from a letter to TorriceUi, written in 1639. (See Montucla, 

 Hist, dea Math.' voL ii. p. 52, *c.) 



CYCLOPEDIA. [DICTIOSABT.] 



CYDER. [CIDEB.J 



CYGNUS (the swan), one of the old constellations of Aratus, who 

 refers it to the fable of Leda, as does Hyginus ; but the Utter gives 

 another fable of the same kind. The bright star (Deueb), a Cygni, 

 may be seen on the meridian at eight o'clock in the beginning of Oc- 

 tober ; the bright stars in AquiU, Lyra, and Cygnus form a remarkable 

 triangle. 



The principal stars ore as follows : 



No. in Catalogue 



Magnitude. 

 4 

 3 

 3 

 4 

 3 

 4 

 2 

 3 

 4 

 4 

 4 

 3 

 4 

 4 

 4 

 4 



CYLINDER, in mathematics (ituAo'Spot), a name given generally to 

 the surface formed by a straight line which moves parallel to itself, 

 whatever may be the guiding curve ; but frequently confined to the 

 common definition, which supposes the straight line to be of finite 

 length, and to move round the circumference of a circle, keeping 

 always at right angles to its plane. We shall extend this a little, and 

 treat of the cylinder which has on oval for its base, and the moving 

 line at right angles to the plane of the base, whence the cylinder in 

 called a ri'jht cylinder. 



The cylinder may be considered us a cone, of which the apex is at 

 an infinite distance ; and many of the general notions in the article 

 COXE may be applied to it. 



The content of a cylinder (in cubic units) is the number of square 

 units in the base multiplied by the number of linear units in the alti- 

 tude. Thus the cylinder being circular, the base having a radius of 

 10 feet, and the altitude being 7 feet, the number of square feet in the 

 base is 100 x 856 ---118, or 314-159, which, multiplied by 7, gives 

 2199'118, the number of cubic feet in the cylinder. To find the num- 

 ber of square unite in the surface, multiply the number of linear units 

 in the circumference of the base by that in the altitude. Thus in the 

 preceding case the number of feet in the circumference of the base U 

 20 x 855---113, or 62-8318, which, multiplied by 7, gives 439-8226, the 

 number of square feet in the cylindrical part of the surface, exclusive 

 of it two terminating planes. [PRISM, SuBCONTBABY.] 



CYLINDRICAL LENS. [LEWS.] 



CYMAMETKR. This name has been given to a contrivance, regis- 



tered by Mr. Fenn a few years ago, for making copies of the outlines 

 of capitals, cornices, mouldings, and other architectural figures. Many 

 rears earlier, a curious plan was adopted for taking a mould of the 

 liuman face, by enclosing a Urge number of thin steel wires in a frame ; 

 pressing it gently and gradually, so that one end of every wire should 

 touch the face, and thus form a die or intaglio of wires, the reverse 

 of the face. Mr. Fenn seems to have conceived his cymometer as an 

 extension of this plan. It consists, essentially, of a Urge number of 

 very thin laths or plates, all of equal length, and placed one on 

 another. When one end of these laths U pressed against a moulding 

 or other device, the other end assumes a corresponding position ; the 

 laths which press against a convex surface jut out more at the other 

 end than those which press against a concave surface ; insomuch that the 

 outer extremities of all the laths form collectively a type of the mould- 

 ing or device. 



CYMBALS (KiWJoXoi-), metallic musical instruments of percussion, 

 which are traceable to the remotest ages of antiquity, and, with no 

 great change in form, are still used by the moderns. They are always 

 in pairs, are made of brass, and, according to Greek sculptures and 

 medals, anciently took, as their name imports, a more cup-like shape 

 than at present Servius says that the cymbals were consecrated to 

 Cybele that is, were employed by her priests because they i 

 sented the two celestial hemispheres which surround the earth. They 

 are now nearly flsjk, about twelve inches in diameter, the Cfnir.il 

 port sunk in, and at the back of the sunken portion is a strap, by 

 which each instrument i held. The sound is produced by striking 

 them more or less violently together, and in the open ah- they produce 

 a very martial effect, but ore entirely out of place in the theatre and 

 concert-room. Into the Utter, indeed, they have not yet often intruded, 

 but in modern theatrical music they take a prominent part when the 

 composer has to make up by noise what he wants in genius and taste. 

 ( YMKNK. [CAMl'HOdEN.] 



CYMIDINE (C,H,,N). An artificial organic base, analogous to 

 aniline. It may be formed by the action of sulphide of ammonium 

 upon nitrocymole (C M H,,NO,). 



CYMnJUM CYMI'NUM, Medical Propertui of. This annual urn- 

 belliferous plant (the generic name of which is moot commonly spelt 

 Cuminum, which mode is correct if it be a mere Latinised form of the 

 Arabian word Qamoun, but incorrect if it be a reduplication of the 

 Greek nv/uyov) is native in Egypt, Ethiopia, &.C., and was cultivated 

 by the ancients in Palestine, as it is by the moderns in Malta, Sicily, 

 and India. The fruit (improperly termed seed) is the officinal part. 

 Externally it is of a grayish yellow colour, and is larger than those of 

 caraway or anise. The seed within more readily separates from the 

 pericarp than happens with most other umbelliferous fruits. It is 

 distinguished from others by having the ridges (juga) prolonged into a 

 point at the summit of the fruit. The primary ridges are five, filiform, 

 and furnished with very fine prickles ; the secondary are four, promi- 

 nent and prickly. Beneath each of these is one vitta. The odour is 

 strong, aromatic, and rather unpleasant ; the taste is warm, bitter, and 

 disagreeable. The odour and taste are mainly due to a vulai 

 which is more abundant in this fruit than in most umbelliferous 

 plants : one pound yields half an ounce of this oil, according to some ; 

 while ten pounds yield only three ounces and a half, according to 

 others. Notwithstanding this large quantity of oil, the fruits are 

 frequently eaten by insects. The oil is pale yellow, bvit speedily 

 becomes brownish, very limpid, of a specific gravity of 0'076. This 

 consists of two distinct oils, one a corbo-hydrogen, belonging to the 

 terebinthinate scries ; the other an oxygenated oil, or hydruret of 

 cumyl. (Pereira.) The odour is, like that of the fruit, disagreeable, 

 and the taste is acrid. When old it becomes acid, and according to 

 Chevallier contains succinic acid. 



The disagreeable odour of cumin seems to have gradually discarded 

 it from medicine for man, and restricted its use to veterinary medicine. 

 Its employment in this way may be a relic of its ancient repute, for 

 the Israelites esteemed it highly as a remedy for cattle after the bites 

 of insects. (Lady Callcott's ' Scripture Herbal,' p. 124.) 



Still it is a potent carminative, and was esteemed by Cullen the best 

 of this class of remedies, a preference to which the very large ]xirti<>n 

 I of essential oil it contains justly entities it. It was reported also dis- 

 cutient and diuretic. In the former quality it was employed as a 

 plaster. It was reckoned one of the semina 4 calida majora. In the 

 north of Europe it is still much used as an addition to bread and 

 ragouts. It enters into the composition of many curry-powders, but 

 should be introduced into these in very small quantity. In Germany 

 a sort of liqueur or aromatic water is distilled from the fruits, useful 

 as a carminative, called kummel-wasser. The seeds of the nigelU 

 saliva are, in the same country, called black cummin. 



CYMOLE (B n H {< ). This substance, met with in oil of cumin, and 

 which also occurs in cool-tor oil, is further formed by the action ( 

 anhydrous phosphoric acid, or of chloride of zinc or camphor. 



C,,H,,0, =C,,H,, + HO 



Camphor. Cymolc. 



It is a colourlexx liquid of an agreeable odour. It is lighter than 

 water, and boils at 347 Fahr. Fuming sulphuric acid forms with it 

 a copulated acid. 





