Page:Cyclopaedia, Chambers - Supplement, Volume 1.djvu/518

 C H O

C H R

The word is derive! from the Greek xfam a cartilage, and 9r% g «yioy, a wing or fin. Of this order are the (bate, ilurgeon, lamprey, &c. CHONDROS, Xvhoc, in antient medical writers, the fame as aKca. Vid. Gorr'. Dcf. Med. See Alica. It ftgnifies alfo fome grumous concretion, as of maftich, or frankincenfe. Caji. Lex. in voc.

Tt is, befides, the Greek word for a cartilage. Gorr. ubi fupra. CHONDROSYNDESMUS, in antient medical writers, figni- fies a cartilaginous ligament. Galen, de Temper. 1. I. c. g. Caft. Lex in voc.

The word is Greek, ^w&oowSierftbf, derived from wfyh a car- tilage, and rtrtJ.fffio, alignment. CHOPIN, a liquid meafure ufed in Scotland, being the half of

their pint. Treat. Pra£t. Geoni. p. 113. CHORAGIUM, in antiquity, was ufed to denote the funeral of a young unmarried woman. Some think it mould be writ coragmm, from xog«, puella, and oywj duco. But Pitifcus choofes rather to derive it from chorus ; becaufe a chorus or company of virgins always attended fuch funerals. Phifc. Lex. Ant. in voc. ChoRAGI'JM fignificd alfo the tiring or dreffing room belonging

to the ftage ; and fometimes was taken for the drefs itfelf CHORAGUS, in antiquity, he who had the fuperintendence of the chorus, whele bufmefs it was to take care they obferved the rules of thermific, and performed their parts with deco- rum. Pitifc. Lex. Ant. in voc. Choragi were likewife certain Athenian citizens chofen an- nually, who were obliged to be at the expence of players, fingers, dancers and mulicians, as often as there was occafion, at the celebration of their public feiKvals. Pott. Archseol. Grxc. 1 i. c. 15. T. 1. p. 86. CHORAIC mufic, mujita choraica, a fort of mufic, proper for

dancing, by the variety of its different motions. CHORAL, choralis, fignifies any perfon that, by virtue of any of the orders of the clergy, was in antient times admitted to fit and ferve God in the choir. Bhunt & Cowcl. Dugdale, in his hiftory of St. Paul's church, fays, that there were with the chorus formerly fix vicars choral belonging to that church. Blount. CHORD (Gycl.) — To find the number of vibrations made by a mufical chord or firing, in a given time, its weight, length, and tenfion being given. LetN reprefent the weight of the chord ; L its length ; P the tenfion, or weight equivalent to it, by which the chord is extended ; and D the length of a given pendulum; * the circumference of a circle, the diameter of which is 1 : then will the number of vibrations made by the given chord, while the pendulum vibrates once, be exprefled

hyp J

DP ■

LN

If we take L for the number of inches and

decimals contained in the length of the chord, and the propor tion of the tenfion to the weight of the chord, as n to 1, thci will the number of vibrations of the chord in one fecond be

. ?'>'> / 3°- 2 ", Where 3-^1 denotes the proportion of the JI3V L 113

circumference to the diameter of the circle; and 39. 2 the length of a pendulum vibrating feconds, in inches and deci- mals of an inch, Engl ifh meafure. This laft expreffion coin- cides with Mr. Euler's rule b, only we here exprefs inEnglifh what he gives in Rhinland meafure. To illuftrate this rule by an example ; fuppofethc length of the chord to be 18. 7 inch- es its weight 6 \ grains, and the tenfion or weight extending this chord to be Sife troy, or 46080 grains. Then a = 18. 7, & n = 4'°"° ._ 7432. The number of vibrations therefore 6. 2

by the rule will he Mi I 3 » ** 7 +& = 39*-- [• Taylor

Method. Increm. Prop. 23. b Tentam. Nov. Theor. Muf. n 6, 7- See alio Mac LaurhH fluxions, Seft. 920.]

By logarithms the rule may be thus exprefled, — [_ C=V.

Where L is the logarithm of the ratio of a pendulum, vi- brating feconds, to the length of the given firings W the logarithm of the ratio of the tenfion to the weight of the firing ; C the logarithm of the ratio of the circumference of a circle to its diameter, or 0.4971500; and laftly, V= loga- rithm of the required number of vibrations in one fecond. In every chord, the number of vibrations in a given time will

be as / ~, that is, as the fquare root of the extending weight

v a divided by the weight of the chord, and its length. If there- fore chords be of the fame length, their vibrations in a given time will Le as the fquare roots of the extending weights, di- vided bv the weights of the chords. If chords be equal in length and weight* their vibrations will be as the fquare roots of their extending weights or tenfions ; and if the tenfions be equal, and the chords differ only in length, their vibrations will be as the fquare roots of their lengths, multiplied by their weight : that is reciprocally as the lengths of the chords, becaufe the weights of the chords will in this cafe be proportional to their lengths. Ruler, ibid. p. 7.

Mr. Euler informs us 3, that he found the chord, making 392 vibrations in a fecond, to be at unifon with the key called a

in inftntments, that h an o£tave and flxth major above the lowell: C in our harpfiehords or vio oncellos. Confcquently the note C, being to a as 3 to 10, will make 1 18 vibrations in one fecond. And the higheft C, or c"', as Mr. Euler ca Is it, being four oc"taves above the loweft c. will vibrate 1888 times in one fecond of time. Mr. Euler fuppofes the limits of the human ear to be, with refpeft to gravity, two octaves lower than C ; and with refpeit to acutenefs, two oclaves higher than c'" b . — [ a Euler, ibid. p. 7, b Ibid p 8. §. 13.] Chord is fometimes alfo ufed for accord. Thus we fay trie common chords to fuch a bafs note, meaning its third, fifih and odtave. Line of Chords. A line of chords is thus made ; let the qua- drant of a circle be divided into 90 degrees, then to its fub- tenfe, or to the chord of 90 decrees, transfer the chord of every arch of the quadrant ; and ihe&chordf, (ct off on the chord of go% and marked refpe£tive!y with the number of degrees in the correfponding arch, do conftitute what is called the line of chords. Treat. PracX Geom. CHORDA membranes tympant. See Chord, CycL CHOREA fancJi vili. See Viti chorea. CHORIZANTES, the name of a feet in Germany, an. 1374, faid to be demoniacs that afFembled in ftrccts and churches. Du Cange, GlofT. Lat. in voc.

We may fuppofe that their enemies called them demoniacs, on account of fome heterodoxy. Du Cange does not men- tion any of their tenets. CHOROIDES (Cycl.) — Some creatures, fuch as the porcupine and fea calf, have the optic nerves inferted into the axis of their eyes. This fait, according to Dr. Porterfield, overturns Mariotte's hypothecs of the choroid's being the principal and immediate organ of fight. Vid. Med. Eil" Edinb. vol. 3. art, 12.

Mr. Le Cat ftrcnuoufly defends Mariotte's opinion, that the choroid coat, and not the retina, is the immediate organ of vifion. The retina, according to him, is to the choroid what the epidermis is to the fkin. Med. EfT. Edinb. Abr. vol. 2. p. 482. CHORO fpezzato, in the Italian mufic, is often met with in- ftead of tutii or da capella, which mean the grand chorus. A doi, a ire, a quatro chor'i, is for two, three, or four chorufTes. When after the name of a part we find prime, i° choro, we muft underftand that it is to be played in the firft chorus; if 2°, II' io, or fecondo choro, the part muft be fung or played in the fecond chorus. And confequently it fhews, that the compo- sition is for eight voices or different parts. Vid. Brojf. Diet. Muf. in voc. CHOUAN, in the materia medica, the name of a fmall feed, called by fome alfo carmine feed. It is a very light and chaffy- feed, in a great meafure refembling worm feed, of an acid tafte, and a yellowifh green colour, but is larger than worm- feed. It is brought into Europe from Turkey, and many parts of the Eaft, and the choice fhould be made of fuch as is largeft, cleaneft, of the greenert colour, and 1 caff fullof fpecks or holes. It is not ufed in medicine, but is of fome value among the people who make carmine for the painters. It is called fantonium viride, or the green worm feed, in our cata- logues of the materia medica, but is unknown in the fhops. Ler/ter/s Di£t. of drugs. CHOUS, in the Eaftern military orders, the title of the mefTen- gers of the divan of janifaries. There are feveral degrees of honour in this poft. When a perfon is firft advanced to it, he is called a cuchuk, or little chous \ after this he is advanced to be the alloy chous, that is, the meffenger of the ceremonies; and from this, having pafled thro' the office of petehr.a, or procurator of the effects of the body, he is advanced to be the has chous. Pocock's Egypt, p. 168. CHOUX, in natural hittory, a name given by the French to a fpecies of fhell fifh of the cordiform or bucardium kind. The French are very fond of a fort of cabbage which they call chouxe decoupc, cut and curled cabbage, and this fhell which is full of tranfverfe lamina; which rife above the furface, and are of an undulated form, very much refembles the leaves of that cabbage; it is truncated at the end,and is covered with longi- tudinal ribs, which are eight or nine in number,and being hol- lowed, not folid, reprefent fo many tubes ; thefe hollows, how- ever, do not penetrate into the fhell, whofe cavity is uniform, thefe hollows only reaching to the thin cover of the whole fifh. Pliny mentions this peculiar fpecies of fhell, and other natura- lifts have not omitted the hiftory of it. Fabius Columns has elegantly defcribed it, and Lifter has given a figure of it twice over, in two different parts of his book. There is another fpe- cies lefs elegant, and wanting the hollowed ribs. F. Colunma, de Purpura, c. 17. p- 36. CharL Excrcit. p. 64. See

CoRDiFORMIS.

CHRABRATE, in natural hiftory, a name given by the writers of the middle ages to a pellucid ftone, faid to have great virtues againft diforders of the liver, and fplcen, and many other ima- ginary qualities. It appears by their defcriptions to have been no other than the common pebble chryftal.

CHREMPS, in ichthyology, a name given by the cldeft Greek writers to the fifh fince called chromis. It is a fpecies of the fpari, and is diftmguifhed by Artedi by the name of the fparus with the fecond ray of the bell v fins very long.

CHRIST-