COM 



COM 



COMPLEMENT of the course, in naviga- 

 tion, is the number of points the course 

 wants of 90, or eight points, viz. of a 

 quarter of the compass. 



COMPLEMENT of life, in the doctrine of 

 annuities, denotes the difference, accord- 

 ing to M. De Moivre's hypothesis, be- 

 tween the age of any given life and 86 

 years. Thus the complement of a life of 

 45 years is 41 : of 30 it is 56. According 

 to this hypothesis, the probabilities of 

 life, through every period of existence, 

 are supposed to decrease in an arithmeti- 

 cal progression, so that out of 86 persons 

 just born, one is supposed to die every 

 year, till at the end of 86 years, which is 

 considered as the utmost limit of human 

 life, the last survivor becomes extinct. 

 On this supposition, the number of years 

 that a person has an equal chance of sur- 

 viving, is made to be the same with the 

 expectation which M. De Moivre finds 

 to be equal to half the complement of 

 life ; so that if the age be 4, the expecta- 

 tion will be -^ =41; if the age be 82, 



4 

 the expectation will be = 2; while the 



chance that a child aged 4 survives 41 



41 

 years is and the chance that a person 



aged 82 survives 2 years is 1. Since each 

 of these fractions is = , it follows that 

 the one has an equal chance of living 41, 

 and the other of living 2 years. But by 

 tables founded on observation, the ex- 

 pectation of these lives are 402 an d 3, 

 while the chance of the younger living 

 40| years is 464, and the chance of the 

 elder living 3 is 53 : that is, in the first 

 instance the chance is less, and in the 

 second greater than an even one, that a 

 person lives such a number of years as 

 shall be equal to his expectation, which 

 proves the incorrectness of M. De 

 Moivre's hypothesis. 



COMPLEMENTS, in a parallelogram, are 

 the two smaller parallelograms made by 

 drawing two right lines through a point 

 in the diagonal, and parallel to the side 

 of a parallelogram. In every parallelo- 

 gram these compliments are equal. 



COMPLEX, terms, or ideas, in logic, are 

 such as are compounded of several sim- 

 ple ones. 



Complex ideas are often considered as 

 single and distinct beings, though they 

 may be made up of several simple ideas, 

 as a body, a spirit, a horse, a flower ; but 

 when several of these ideas of a different 

 kind are joined together, which are wont 



to be considered as distinct, single be- 

 ings, they are called a compounded idea, 

 whether these united ideas be simple or 

 complex. Complex ideas, however com- 

 pounded and recompounded, though 

 their number be infinite, and their va- 

 riety endless, may be all reduced under 

 these three heads, modes, substances, and 

 relations. 



COMPLEX proposition, is either that 

 which has at least one of its terms com- 

 plex, or such as contains several mem- 

 bers, as causal propositions ; or it is seve- 

 ral ideas offering themselves to our 

 thoughts at once, whereby we are led to 

 affirm the same thing of different objects, 

 or different things of the same object. 

 Thus, " God is infinitely wise, and infi- 

 nitely powerful." In like manner, hi the 

 proposition, " Neither kings nor people 

 are exempt from death. 



COMPLEXION, a term technically 

 denoting the temperament, habitude, 

 and natural disposition of the body ; but 

 popularly signifying the colour of the 

 face and skin. Few subjects have en- 

 gaged the attention of naturalists more 

 than the diversities among the human 

 species, among which that of colour is the 

 most remarkable. The great differences 

 in this respect have given occasion to 

 several authors to assert, that the whole 

 human race have not sprung from one 

 original : but that as many different spe- 

 cies of men were at first created, as there 

 are now different colours to be found 

 among them. It remains, in reality, a 

 matter of no small difficulty, to account 

 for the remarkable variations of colour 

 that are to be found among different na- 

 tions. Dr Hunter, who considered the 

 matter more accurately than has common- 

 ly been done, determines absolutely 

 against any specific difference among 

 mankind. He introduces his subject by 

 observing, that when the question has 

 been agitated, whether all the human 

 race constituted only one species or not, 

 much confusion has arisen from the sense 

 in which the term species has been 

 adopted. He therefore thinks it neces- 

 sary to set out with a definition of the 

 term. He includes under the same spe- 

 cies all those animals which produce issue 

 capable of propagating others resem- 

 bling the original stock from whence 

 they sprung. This definition he illus- 

 trates by having recourse to the human 

 species as an example. And in this sense 

 of the term he concludes,that all of them 

 are to be considered as belonging to the 

 same species. And as, in the case of 

 plants, one species comprehends several 



