DIS DISMAL SWAMP. 



689 



party really taxed is the one who pays the tax to the 

 government. See Taxes, and Revenue. 



DIS ; among the Romans, a name of Pluto (q. v.) 

 and Hades. 



DISCORD. A discord is a dissonant or inharmo- 

 nious combination of sounds, so called in opposition 

 to the concord, the effects of which the discord is cal- 

 culated to relieve and sweeten. Among various other 

 discords, are those formed by the union of the fifth 

 with the sixth, the fourth with the fifth, the seventh 

 with the eighth, and the third with the ninth and 

 seventh, all which require to be introduced by certain 

 preparatives, and to be succeeded by concords to 

 which they have some relation. 



DISCOUNT, or REBATE, is an allowance made 

 on a bill, or any other debt not yet become due, in 

 consideration of present payment. Bankers, mer- 

 chants, &c. , allow for discount a sum equal to the in- 

 terest of the bill for the time before it becomes due, 

 which, however, is not just ; for, as the true value of 

 the discount is equal to the difference between the 

 debt and its present worth, it is equal only to the in- 

 terest of that present worth, instead of the interest on 

 the whole debt. And, therefore, the rule for finding 

 the true discount is this: As the amount of l and 

 interest for the given rate and time is to the given 

 sum or debt, so is the interest of 1 for the given 

 rate and time to the discount of the debt. Thus, if 

 the interest or discount of money were five per cent., 

 then the allowance on a bill ot 100 would be found 

 thus : As 21*. : .100 ::!*.: 4 15s. 2$d. 



DISCUS, DISC, or DISK ; among the Greeks and 

 Romans, a quoit of stone or metal, convex on both its 

 sides, perforated in the middle, and fastened to the 

 hand by strings. Throwing the discus 



was one of the gymnastic exercises ; and in the 

 Olympic and other games, it was considered a great 

 honour to conquer in the contest. Perseus is said to 

 have invented this instrument, and Apollo killed his 

 favourite, Hyacinth, with it. In some places, the 

 plate which contains the host during the act of con- 

 secration, is called disk. 



Disk, in astronomy, means the face of the sun and 

 moon, as they appear to observers on the earth. 



DISEASES, HEREDITARY. The influence of the 



parents on the organization of the child Is so greats 

 that even the individual peculiarities which distin- 

 guish one man from another are, in part at least, 

 transmitted to his children ; hence the similarity, in 

 person and looks, of the child to its parents. The 

 internal organs, too, as well as the external form, 

 have the same resemblance ; so that the peculiar 

 constitution, the greater or less activity and devel- 

 opment of these organs, are found to pass from parent 

 to child. Now, as it is the particular state of the 

 several organs and functions, in which a very great 

 part of diseases have their foundation, it follows that 

 these diseases may be inherited and, in fact, it has 

 been observed, that the son is not unfrequently at- 

 tacked by a disease at the same period of life in 

 which his father was. These diseases are called 

 hereditary ; but it is only the predisposition to them 

 that is, properly speaking inherited. Hence the 

 actual development of hereditary diseases requires 

 certain co-operatmg circumstances. Constitutional 

 diseases are very often not hereditary, but depend on 

 circumstances which affect the foetus during preg- 

 nancy. The father has no influence on the child, 

 beyond the. act of generation ; the mother operates 

 upon it during pregnancy, and it is possible that 

 hereby occasion may be given to hereditary diseases. 

 Among the diseases which are most frequently here- 

 ditary, are scrofula, bleeding (especially at the lungs) 

 and hemorrhoids, consumption, gout, the gravel and 

 stone, scirrhus av>d cancer, disorders of the mind 

 and spirits, hysterical and hypochondriac affections, 

 apoplexy, epilepsy, and organic diseases of particular 

 parts, especially of the heart. They have this pe- 

 culiarity, that' they are produced, and appear as con- 

 stitutional diseases, more from the action of internal 

 than of external, of predisposing than of occasional 

 causes. Such diseases are much more difficult to 

 reach and to cure than those which originate in 

 accidental external causes. Hence it is especially 

 necessary to prevent in season their growth and 

 development. The means of doing this are the fol- 

 lowing : 1. Whoever has a hereditary predisposition 

 to any disease, should not marry one who has the 

 same constitution. For this reason, marriages be- 

 tween near relations are not advisable, as tending to 

 perpetuate such hereditary diseases. This, too, ap- 

 pears to be the reason why attachments are generally 

 formed between persons of opposite constitution and 

 different temperament. 2. We ought to order all 

 the circumstances, in which the child grows up, in 

 such a way, that the inherited predisposition may 

 not only not be favoured, but counteracted. 3. The 

 accidental occasions which favour the growth of the 

 disease should be avoided, especially at the time of 

 life in which the father was attacked by it. The 

 medical treatment of hereditary diseases is not es- 

 sentially different from that which is requisite in the 

 same diseases, arising under different circumstances. 

 DISHING WHEELS. Wheels should be exactly 

 cylindrical, if roads were, in all cases, level and 

 smooth ; but since the unequal surface of most roads 

 exposes carriages to frequent and sudden changes of 

 position, it is found advantageous to make the wheels 

 a little conical, or, as it is commonly called, dithing, 

 so that the spokes may all diverge with their extrem- 

 ities from the carriage. 



DISMAL SWAMP; a large tract of marshy 

 land, in America, beginning a little south of Nor- 

 folk, in Virginia, and extending into North Ca- 

 rolina, containing 150,000 acres : thirty miles long, 

 from north to south, and ten broad. This tract is 

 entirely covered with trees, some of which grow to a 

 very large size ; and between them the brushwood 

 springs up so thick, that many parts are utterly im- 

 pervious. In the midst of the swamp is a lake, called 



