DEF 



DEG 



whereas in the quality of King, de JRoy, 

 the articles a/and de mark nothing pre- 

 cise, and arc therefore indefinite. 



DEFINITION, the shewing the mean- 

 ing of one word by several other not sy- 

 nonymous terms. The meaning of words 

 being only the ideas they are made to 

 stand for by him that uses them, the 

 meaning of any term is then shewed, or 

 the word is defined, when by other words 

 the idea it is made the sign of, and is an- 

 nexed to it in the mind of the speaker, 

 is, as it were, represented and set before 

 the view of another ; and thus its signifi- 

 cation is ascertained This is the only 

 end and use of definitions, and therefore 

 the only measure of what is, or is not, a 

 good definition. 



The names then of simple ideas are 

 incapable of being defined, because the 

 several terms of a definition signifying 

 several ideas, they can altogether by no 

 means represent an idea which has no 

 composition at all ; and therefore a defi- 

 nition, which is properly but shewing 

 the meaning of any one word by several 

 others, not signifying the same each, can 

 in the names of simple ideas have no 

 place. Definitions which then take place 

 in compound ideas only are of two sorts : 

 the definition of the name, which is the 

 explanation of what any word means ; 

 and the definition of the thing, which 

 explains in what the nature of that thing 

 consists. 



The special rules for a good definition 

 are these : 1. A definition must be uni- 

 versal, or adequate, that is, it must agree 

 to all the particular species, or individuals, 

 that are included under the same idea. 

 2. It must be proper, and peculiar to the 

 thing defined, and agree to that alone. 

 These two rules being observed, will al- 

 ways render a definition reciprocal with 

 the thing defined, that is, the definition 

 may be used in the place of the thing de- 

 fined ; or they may be mutually affirmed 

 concerning each other. 3. A definition'" 

 should be clear and plain ; and indeed it 

 is a general rule concerning the defini- 

 tion both of names and things, that no 

 word should be used in either of them, 

 which has any difficulty in it, unless it 

 has been before defined. 4. A definition 

 should be short, so that it must have no 

 tautology in it, nor any words superflu- 

 ous. 5. Neither the thing defined, nor a 

 mere synonymous name, should make 

 any part of the definition. 



DEFLAGRATION, in chemistry, the 

 act of burning two or more Substances to- 

 gether, as charcoal and nitre. When a 

 quantity of nitre, (nitrate of potash,) is 



mixed with an equal weight of sulphur, 

 charcoal, or other inflammable substance, 

 if the mixture is thrown into a crucible 

 heated to redness, a very vivid combus- 

 tion is instantly excited : this is deflagra- 

 tion, which is thus explained : nitre is a 

 compound of nitric acid and potash : ni- 

 tric acid consists of nitrogen and oxygen ; 

 the nitre, therefore, contains a large por- 

 tion of oxygen, which is in so weak a 

 state of combination, that it Is separated 

 by exposure to a red heat. When, 

 therefore, the mixture of the nitre and 

 of the inflammable body is thrown into 

 the heated crucible, the oxygen of the 

 former is disengaged ; it is thus suddenly 

 presented to the inflammable body, and 

 hence the vivid combustion that is excit- 

 ed ; and for the production of this, it is 

 not even requisite to raise the tempera- 

 ture so high as that which would be ne- 

 cessary, if applied alone, to decompose 

 the nitre, the affinity of the inflammable 

 body to the oxygen of the nitre causing 

 it to take place at a temperature somewhat 

 lower. The nitrogen, or azote of the nitric 

 acid, passes oft' in the state of gas, and 

 the potash with which the acid was united 

 remains mixed, or united with the body 

 formed by the combination of the oxy- 

 gen, and the inflammable substance. 



DEFORMITY, the want of that unifor- 

 mity necessary to constitute the beauty of 

 an object. See BEAUTY". 



DEGLUTITION, in medicine, the act 

 of swallowing the food, performed by 

 means of the tongue driving the aliment 

 into the oesophagus, which, by the con- 

 traction of the sphincter, protrudes the 

 contents downwards. 



DEGRADATION, a punishment of de- 

 Iinque.nl ecclesiastics. The canon-law 

 distinguishes it into two sorts ; the one 

 summary, by word only ; the other so- 

 lemn, by stripping the person degraded 

 of those ornaments and rights which are 

 the ensigns of his order or degree. 

 C DEGRADED cross, in heraldry, a cross 

 divided into steps at each end, diminish- 

 ing as they ascend towards the centre, 

 called by the French perronjite. 



DEGREE, in geometry, a division of a 

 circle, including a three hundred and six- 

 tieth part of its circumference. Every 

 circle is supposed to be divided into 

 three hundred and sixty parts, called de- 

 grees, and each degree divided into sixty 

 other parts, called minutes ; each of these 

 minutes being again divided into sixty 

 seconds, each second into thirds, and 

 each third into fourths, and so on. By 

 this means no more degrees or parts are 

 reckoned in the greatest circle than in 



