RAT 



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pounded with alcohol, Mi^ar, and the 

 odoriferous principles of vegetables, espe- 

 cially of the bruised seeds of cherries, 

 apricots, and peaches. 



HATCH. In mechanics, a bar contain- 

 ing angular teeth, into which a pall drops 

 to prevent machines from running back. 



RATCH'ET (of a watch). A small tooth 

 at the bottom of the fusee, which stops 

 it in winding up. 



RATCH'ET-WHEEL. 1. A circular ratch. 



2. The ratchet-wheel of a clock is a 



sort of wheel which has twelve fangs, 

 that serve to lift the dents every hour, 

 and thereby cause the clock to strike. 



RATCH'IL. Among miners, fragments 

 of stone. 



KATE. 1. A tax assessed for public 



use, as parish rates. 2. In the navy, 



the order or class of a ship according to 

 its magnitude or force. Ships of the first 

 rate mount 100 guns, or upwards ; those 

 of the second rate carry from 90 to 98 

 guns ; those of the third rate from 64 to 

 80 ; those of the fourth rate from 50 to 60 ; 

 those of the fifth rate from 32 to 44 ; those 

 of the sixth rate from 20 to 30 guns. 

 Those of the latter rates are calledfrigates. 



RAT'ELUS, ) A subgenus of the class 



RAT'EL. / Mammalia : order Carna- 

 ria : family Carnirora : tribe Plantigrada. 

 One species only is known, the Viverra 

 tnellivora, Sparm., of the Cape of Good 

 Hope. It is about the size of the European 

 badger, and digs up the earth with its 

 long paws, in search of the honey-combs 

 of the wild-bees, on which it feeds. 



RA'TIO, Lat. from ratus, rear, to con- 

 firm. The relation which one quantity 

 bears to another in respect of magnitude ; 

 the comparison being made by consider- 

 ing how often the one magnitude con- 

 tains the other. Thus the ratio of 6 to 3 

 is S- or 2, and the ratio of 4 to 5 is ^., which 

 may be written 4:5. This is geometrical 

 ratio, and is that which is signified when 

 the term is used without any distinctive 

 . epithet ; but arithmetical ratio is the dif- 

 ference between two quantities. Thus 

 th< arithmetical ratio of 2 to 5 is 3. Ratio 

 respects magnitudes of the same kind 

 only. Thus one line has a certain ratio 

 to another line, but not to a surface. 



RA'TION, Fr. from ratio, a proportionate 

 quantity. A fixed allowance of provisions, 

 drink, and forage, assigned to each soldier 

 in any army for his daily subsistence, and 

 for the subsistence of horses. 



RA'TIONAL. 1. In arithmetic and alge- 

 bra, an expression in finite terms. 2. 



In geography, the rational horizon is a 

 plane passing through the centre of the 

 earth, parallel to the sensible horizon, at 

 the place of observation. 



RA'TIOMALE (French). 1. A detail with 

 reasons assigned. 2. An account of a 



solution of the principlesof some opinion, 

 action, hypothesis, phenomenon, &c. 



RA'TioNALiSTs,from reason. Rational- 

 ists may be said to comprehend those 

 latitudinarians who consider the super- 

 natural events of the Old and New Testa- 

 ments as events happening in the ordi- 

 nary course of nature, but described by 

 writers, without any real ground, as 

 supernatural, and who consider the mo- 

 rality of the Scriptures as subject to the 

 test of human reason. 



RAT'LINS, \ Small lines traversing the 



RAT'LINFS. j shrouds of a ship, making 

 the step of a ladder for ascending to the 

 mast head. 



RAT MOLE. In zoology , a name common 

 to two small quadrupeds, the Zanni, 

 Slepez, or Blind Rat-mole (Spalax typhus, 

 Gulden), which is rather larger than our 

 rat, and lives under ground like the mole -, 

 and the Maritine Rat-mole (Sathyergits 

 maritimus, Illiger), nearly the size of a 

 rabbit, and furnished with a short tail, 

 and visible eyes. ^ 



RATO'ON, Sp. ratono. A sprout from 

 the root of the sugar-cane which has 

 been cut. 



RAT'TANS. Canes. The long slender 

 shoots of the Calamus rotang, a prickly 

 bush , and one of the most useful plants of 

 the Malay peninsula, and Eastern islands. 

 Called by the Malays rotan, and by the 

 Javanese rottang. They are extensively 

 used for cane- work, and are a consider- 

 able article of trade. 



RAT-TAIL. In farriery, an excrescence 

 grow in if upon the pastern to the middle 

 of the shank of a horse. 



RATTEEN', Sp. ratina. A thick woollen 

 stuff, quilted or twilled. 



RATTIXET'. A woollen stuff, somewhat 

 thinner and lighter than ratteen. 



RAT'TLES. In pathology, a popular name 

 for the rattle-like noisy breathing often 

 heard in persons who are in articulo mor- 

 tis, and which arises from the accumula- 

 tion of mucus in the air-passages. In 

 nosology, a popular name of croup, or 

 cynanche trachealis. 



RAT'TLESNAKES. A genus of venomous 

 snakes (Crotalus, Lin.), all distinguished 

 by the rattle which terminates the tail. 

 See CROTALUS. 



RAT'TLF.SXAKE-ROOT. A plant ; the Po- 

 lygala Senega, the root of which was for- 

 merly deemed a specific against the poison 

 of the rattlesnake. It is still used as an 

 antiphlogistic. 



RAV'ELIN (French). In fortification, a 

 detached work, with two faces, which 

 make a salient angle without any flanks ; 

 it is raised before the curtain of the 

 place. In this it differs from a half-moon, 

 which is placed before an angle. 



RA'VES. A bird (the Corvus cornx, Lin.), 

 noted for its entirely black plumage. It 



