COMB COMBUSTION. 



339 



changing it into a line, has been removed, in modern 

 times, by the practice of making the columns consist 

 of only one battalion, and by disposing these single 

 battalions near each other in such a way as to sup- 

 port one another by their fire, instead of arranging 

 them uselessly behind each other. By the usual 

 way of forming the columns towards the centre, 

 those have received such a movability and facility of 

 development, that a line may be restored in two 

 or three minutes. Almost all battles are fought, at 

 present, by such small columns, which, when the 

 order in line is judged more for the purpose, may be 

 changed into lines, and which, besides, form the best 

 squares for resistance against attacks of cavalry, by 

 presenting a front to all sides, and unite many other 

 advantages. In the case of cavalry, also, attacks 

 may be made either in column or in line. The 

 charge in close columns, which is in use particularly 

 ' with the French, is of the greatest effect when it 

 succeeds ; but when it fails the whole body of assail- 

 ants is exposed to annihilation, or to rout, as no sup- 

 port, no development, nor orderly retreat, is pos- 

 sible. The attack with columns at some distance 

 from each other has this advantage, that, if the first 

 division fails, the subsequent ones may succeed ; 

 moreover, the facility of manoeuvring is much 

 greater. This mode of attack is particularly advis- 

 able in assaulting squares of infantry. Marching and 

 fighting in lines, however, are the modes usually 

 practised by cavalry ^ Column-roads are such roads 

 as may be passed with all kinds of arms : when the 

 ordinary road is ruined, they are laid out across the 

 fields, and marked by poles with straw (Jalons). 



COMB (camb, SAXON) ; an instrument to separate 

 and adjust the hair, too well known to need descrip- 

 tion. We have no certain authority, either from 

 busts or medals, that either the Greek or the Etrus- 

 can women used this useful and ornamental appen- 

 dage to their hair ; although, in most of them, it is 

 carefully and gracefully arranged. Nor in the 

 articles that have been disinterred at Volterra and 

 other Etruscan cities, where abundance of utensils 

 and instruments of the female toilet have been found, 

 has there been a single comb discovered. There is, 

 therefore, no authority, with which we are at pre- 

 sent acquainted, to inform us from whom the Ro- 

 mans borrowed this article of the toilet. Many of 

 their sepulchral inscriptions are dedicated to their 

 dressing maids (ornatrices). It is probable that the 

 combs of the Romans were of ivory, box, gold, and 

 silver; but, according to Guasco, they were also of 

 iron and of bronze. In the work of that author, Delle 

 Ornatrici, there are several representations of an- 

 cient Roman combs. One, in particular, at page 63, 

 that was in the museum Setala, at Milan, is a long 

 one of box, of which the handle is overlaid with 

 ivory, and appears to have been ornamented with a 

 small meander in gold. It has two rows of fine 

 teeth, delicately wrought and well proportioned. 

 Canova and other modern sculptors have made great 

 use of the comb in their female busts, to which they 

 add a grace and elegance unknown to those of the 

 ancients. 



COMBAT, in law, or SINGLE COMBAT, deno'es a 

 formal trial, between two champions, of some doubt- 

 ful cause or quarrel, by the sword or batoon. This 

 barbarous way of deciding controversies was, in the 

 middle ages, very common, not only in criminal, but 

 also in civil causes. The form and ceremony of the 

 combat are described in the Grand coutumier of Nor- 

 mandy. The accuser first swore to the truth of his 

 accusation ; the accused gave him the lie ; upon 

 which he threw down a pledge of battle, and the 

 parties were committed to prison till the day of com- 

 bat. The legal combat belongs to the same class of 



absurdities as the formal trial of witches. See Duel 

 and Champion. 



COMBINATION, in Mathematics, Is the varia- 

 tion or alteration of any number of figures, letters, 

 colours, sounds, &c., in all the different manners pos- 

 sible. The parts combined are called elements. 

 The doctrine of combination is that branch of mathe- 

 matics which teaches the results arising from all pos- 

 sible combinations, and gives rules respecting them. 

 Combinatory analysis is the application of the doc- 

 trine of combination to analysis, and constitutes a 

 branch of science often very involved. A system of 

 characters is appropriated to this purpose. Hinden- 

 burg, of Leipsic, in 1778, gave it the character of 

 an independent science ; and it has been of impor- 

 tant service in relation to the higher branches of 

 mathematics. (See Weingartner's Lehrbuch der mn- 

 binatorischen Analysis, Leipsic, 1801, 2 vols.) Per- 

 mutations are those combinations in which, each time, 

 all the elements are used, and the object is to deter- 

 mine how often they change their place, for instance, 

 abed, acb d, bdac, &c. The number of possible 

 changes or combinations is found by multiplying the 

 terms 1, 2, 3, &c., continually into each other; thus, 

 2x3=6; 6x4=24; 24x5=120, &C. Thus the 

 combinations of five quantities amount to 120. The 

 changes that may be rung on twelve bells amount to 

 479,001,600 ; and the twenty-four letters of the al- 

 phabet admit of 62,044,840,173,323,943,936,000 

 changes or combinations. 



COMBUSTION. It is not easy to give a correct 

 definition, or to assign a general cause, of this fami- 

 liar phenomenon. It may, however, be described as 

 the result of the combination of two or more bodies, 

 attended with a disengagement of heat and light. 

 This description distinguishes combustion from igni- 

 tion, which is merely the result of an elevation of 

 the temperature, without any chemical combination. 

 Fire was formerly considered as an element, which 

 had the power of converting certain bodies into its 

 own nature ; but the progress of chemical science 

 soon showed the error of this notion. Stahl's cele- 

 brated theory was founded on the hypothesis of the 

 existence of a substance which he called phlogiston. 

 Every combustible body was supposed to contain this 

 substance, which was disengaged by combustion : the 

 loss of the phlogiston was the cause of the residuum 

 being incombustible. The heat and light were attri- 

 buted to the violent agitation of the phlogiston at 

 the moment of its disengagement. The discoveries 

 of Black and Priestley opened the way to the system 

 of Lavoisier, which, in 1785, entirely supplanted the 

 theory of Stahl. During the conversion of solids 

 into fluids, and of fluids into vapours, there is a con- 

 siderable absorption of heat : when, on the contrary, 

 vapours and liquids are restored to the fluid and solid 

 form, the heat which they contain is evolved, and 

 passes from the latent to the sensible state. (See 

 Caloric.) These views were assumed by Lavoisier 

 as the basis of his fieory. Oxygen gas was con- 

 sidered as a compound of a peculiar basis, united to 

 the matter of light and heat, and combustion as the 

 combination of oxygen with the burning body. Dur- 

 ing the combustion, the basis, combining with the 

 combustible, augmented its weight and changed its 

 properties ; while the imponderable elements of the 

 gas light and heat were developed in the form ot 

 flame. But facts prove this theory incorrect. In 

 the first place, all the phenomena of combustion take 

 place, in many cases, without the presence of oxy- 

 gen. In the second place, there are many cases in 

 which oxygen unites with bodies, without the evo- 

 lution of light and heat, as during the change of 

 some metals on exposure to the air. And, further, 

 there are many instances in which combustion takes 

 r 2 



