had it in our power to exhibit the phænomenon of the electric spark, which is electricity producing ignition by breaking through a non-conductor, if we had not fortuitously experimented in circumstances where the electricity is first made to take the form of a charge, and afterwards brought into a state of considerable intensity, by separating those bodies from each other, which produced the compensation by their opposite states. Thus in the electrical machine, (see Nicholson, in the Philos. Trans. 1789,) little or no electric signs are produced by a cylinder rubbed by a very flat amalgamed leather, terminating in a neat line of contact. But this rubber and cylinder will, without any alteration, afford electricity, if a flat piece of metal, or the hand, or any other flat conductor, be held over that part of the cylinder which is in the act of receding from the cushion, even though this conductor be held at the distance of an inch or more, without touching either the cylinder or its rubber. It is proved from experiment, that the conducting body thus presented acquires the opposite state, and enables the cylinder to carry off a greater quantity of electricity in the form of a charge, the interposed air being the electric.

When the cushion is thick and rounded, as is the case with the human hand, which was first used for this purpose, the rounded part opposite the receding surface of the cylinder, performs the office of compensation; and the best application which has yet been made for this purpose, is that of a flap of silk proceeding from beneath the cushion, which assumes the negative state, so as to compensate the positive state on the cylinder, in a very considerable charge, which is conveyed by the rotation to the farther end of the silk, where it becomes uncompensated electricity upon the naked surface, at an intensity which could not otherwise have been produced.

It has not yet been determined what are the conditions and circumstances of the change which takes place by the action of the air at the face of the rubber, nor why the surface of the glass should become positive when rubbed with one kind of rubber, as for example, the human hand; and negative, if rubbed with another kind, such as cat-skin, or flannel, nor why glass, deprived of its polish, becomes negative with rubbers which would have rendered smooth glass positive. The most rational conjecture seems to be, that the surface which is most

heated in consequence of its roughness, or the relative smallness of its dimensions, acquires the negative state.

There is a certain velocity of rotation, which is about five feet per second, at which the excitation of electricity by a cylinder nearly vanishes; but it returns again, the moment the velocity is diminished. Some who maintain the existence of a material cause of heat, or caloric, are disposed to consider electricity as one of the states of caloric, in which the matter of heat can pass through bodies without raising their temperature, and with much greater velocity than that by which temperature is communicated.

From the imperfect knowledge we possess respecting excitation, it is very difficult for the most experienced electricians to excite a cylinder with certainty and power. If the cylinder be greased all over with tallow, and then turned for some time in contact with the cushion, the silk flap being thrown back, and an amalgamed leather be applied and rubbed about upon the surface of the cylinder in motion, electrie sparks are soon produced in abundance; and if the silk be then thrown again into contact with the cylinder the excitation will, in general, be strong; but it is seldom so strong at the first time of exciting as it proves to be after the expiration of a day

or more.

It seems as if the amalgam and tallow required a considerable time of working to be brought into the best state for excitation.

In order to judge of the degree of intensity of an excited cylinder, we must have recourse to some standard of the quantity of effect produced by the friction of a given surface. It has not been shewn that much, if any thing, depends on the thickness of the glass, though some kinds of glass are more excitable than others, and some not at all so. If a coated electric jar be taken of about one-twentieth of an inch in thickness (see JAR, electric), a cylinder or plate, moderately excited, will require fifty or sixty square feet to pass the cushion, in order to charge one foot of the coated glass, so as to explode over a rim of three inches, which is as much as can be admitted without danger of the explosion breaking through the jar. If the excitation be stronger, the charge may be made by the friction of thirty feet to one of the jar; and the strongest excitation the editor has ever known, has been by the friction of fourteen square feet of a cylinder to charge one foot

of glass. But as the labour increases by adhesion of the cushion, the stronger the excitation, it seems as if the strength of a man would be more profitably employed in turning two or more plates, or cylinders, at the intensity of thirty feet, than at any higher intensity; besides which, this power is less variable, and may last five or six hours without requiring fresh amalgam.

The vulgar notion of electricity is, that it is fire which passes in a spark from one body to another. From its passage through dense conductors, as well as through the air, it seems to move with extreme velocity; and this may be sufficient, without supposing it to be essentially luminous, to account for the ignited appearance it affords, in all non-conductors, whether air, or oil, or glass, or wood, &c. and even in metal, when the conductor is small. If oxygen be present, these bodies will have their combustible parts burned; and if not, a decomposition of those parts which are ignited

Other figures are the language of some particular passion, but this expresses them all. It is the voice of nature, when she is in concern and transport.

EXCLUSION, or Bill of Exclusion, a bill proposed about the close of the reign of King Charles II. for excluding the Duke of York, the King's brother, from the throne, on account of his being a papist.

EXCLUSION, in mathematics, is a method of coming at the solution of numerical problems, by previously throwing out of our consideration such numbers as are of no use in solving the question.

EXCLUSIVE is sometimes used adjectively, thus: "A patent carries with it an exclusive privilege;” and sometimes adverbially, as, "He sent him all the numbers from N° 145 to N° 247 exclusive;" that is, all between these two numbers, which themselves were excepted.

EXCLUSIVE propositions, in logic, are

those where the predicate 30 agrees with its subject, as to exclude every other. Thus, "Virtue alone constitutes nobility," is an exclusive proposition.

EXCOECARIA, in botany, a genus of the Dioecia Triandria class and order. Natural order of Tricoccæ. Euphorbiæ, Jussieu. Essential character: ament naked; calyx and corolla, nohe; styles three ; capsule, tricoccous. There are two species; viz. E. agallocha and E. Cochin Chinensis. EXCOMMUNICATION, in law, is of two kinds, the less and the greater, which last is the highest ecclesiastical censure which can be pronounced; for thereby the party is excluded from the body of the church, and disabled from bringing any action in the common law courts; he is also disabled to serve on juries, or to be a witness in any cause; he cannot be attorney or procurator for another; he is to be turned out of the church by the churchwardens, and not to be allowed christian burial. He may also, in some cases, be imprisoned until he submits to the ecclesiastical jurisdiction, as in case of refusing to answer to a suit for tithes.

EXCORIATION, in medicine and surgery, the galling or rubbing off of the cuticle. To remedy this, the parts affected may be washed often with warm water, and hartshorn, but especially tutty, lapis calasprinkled with drying powders, as chalk, loosely in a rag, and the powder shook out minaris, and ceruse, which may be tied on the disordered places.

EXCREMENT. See FECES.

EXCRESCENCE, in surgery, denotes every preternatural tumour which arises upon the skin, either in the form of a wart or tubercle.

EXCRETION, or SECRETION, in medicine, a separation of some fluid, mixed with the blood by means of the glands. See SECRETION.

EXCRETORY, in anatomy, a term applied to certain little ducts or vessels, destined for the reception of a fluid, secreted in certain glandules, and other viscera, for the excretion of it in the appropriated places.

EXECUTION, in law, is a judicial writ, grounded on the judgment of the court whence it issues; and is supposed to be granted by the court, at the request of the party at whose suit it is issued, to give him satisfaction on the judgment which he hath obtained; and therefore an execution cannot be sued out in one court, upon a judg

ment obtained in another. These are of different sorts, according to the nature of the action in actions where money is recovered, as a debt or damages, they are of five sorts; 1, against the body of the defendant; 2, or against his goods or chattels; 3, against his goods and the profits of his lands; 4, against the goods and the possession of his lands; 5, against all three, his body, lands, and goods.

EXECUTION of criminals, must be according to the judgment; and the King cannot alter a judgment from hanging to beheading, because no execution can be warranted, unless it be pursuant to the judgment.

This being the completion of human punishment, in all cases, as well capital as otherwise, must be performed by the legal officer, the sheriff or his deputy. Murderers are to be executed the day next but one after conviction, unless it be Sunday, and anatomized; for which reason they are generally tried on a Friday.

EXECUTION, in music, a term applicable to every species of musical performance; but more particularly used to express a facility of voice or finger in running rapid divisions, and other difficult and intricate passages: it includes, in a general sense, taste, feeling, grace, and expression.

EXECUTOR, in law, is a person appointed by the testator to carry into execution his will and testament after his decease. The regular mode of appointing an executor, is by naming him expressly in the will; but any words indicating an intention of the testator to appoint an executor, will be deemed a sufficient appointment.

Any person capable of making a will is also capable of being an executor; but in some cases, persons who are incapable of making a will, may nevertheless act as executors, as infants, or married women; to obviate, however, inconveniences which have occurred respecting the former, it is enacted by stat. 38 Geo. III. c. 89, that where an infant is sole executor, administration, with the will annexed, shall be granted to the guardian of such infant, or such other person, as the spiritual court shall think fit, until such infant shall have attained the age of 21; when, and not before, probate of the will shall be granted him. An executor derives his authority from the will, and not from the probate, and is therefore authorised to do many acts in execution of the will, even before it is proved, such as releasing, paying, or receiv

ing of debts, assenting to licences, &c.; but he cannot proceed at law until he have obtained probate. If an executor die before probate, administration must be taken out with the will annexed; but if an executor die, his executor will be executor to the first testator, and no fresh probate will be needed: it will be sufficient if one only of the executors prove the will; but if all refuse to prove, they cannot afterwards administer, or in any respect act as executors. If an executor become a bankrupt, the court of Chancery will appoint a receiver of the testator's effects, as it will also upon the application of a creditor, if he appear to be wasting the assets. If an executor once administer, he cannot afterwards renounce. If an executor refuse to take upon him the execution of the will, he shall lose his legacy under it. If a creditor constitute his debtor his executor, this is at law a dis charge of the debt, whether the executor act or not, provided however, there be assets sufficient to discharge the debts of the testator: in equity, however, there are some exceptions to this rule. The first duty of an executor or administrator is, to bury the deceased in a suitable manner; and if the executor exceed what is necessary in this respect, it will be a waste of the substance of the testator. The next thing to be done by the executor, is to prove the will, which may be done either in the common form, by taking the oath to make due distribution, &c.; or in a more solemn mode, by witnesses to its execution. By stat. 37 Geo. III. c. 9, s. 10, every person who shall administer the personal estate of any person dying, without proving the will of the deceased, or taking out letters of administration within six calendar months after such person's decease, shall forfeit 501.

If all the goods of the deceased lie within the same jurisdiction, the probate is to be made before the ordinary or bishop of the diocese, where the deceased resided; but if he had goods and chattels to the value of 51. in two distinct dioceses or jurisdictions, the will must be proved before the metropolitan or archbishop of the province in which the deceased died. An executor, by virtue of the will of the testator, has an interest in all the goods and chattels, whether real or personal, in possession or in action of the deceased; and all goods and effects coming to his hands will be the assets to make him chargeable, to creditors and legatees. An executor or administrator stands

in any of the courts at Westminster, under the seal of each court; which exemplifications may be given in evidence to a jury. It is held that nothing but matter of record ought to be exemplified.

EXERCISE, among physicians, such an agitation of the body as produces salutary effects in the animal economy. Exercise may be said to be either active or passive. The active is walking, hunting, dancing, playing at bowls and the like; as also speaking, and other labour of the body and mind; the passive is riding in a coach, on horseback, or in any other manner. Exercise may be continued to a beginning of weariness, and ought to be used before dinner, in a pure light air; for which reason, journies and going into the country contribute greatly to preserve and re-establish health.

EXERCISE, in military affairs, is the ranging a body of soldiers in form of battle, and making them perform the several motions and military evolutions with different management of their arms, in order to make them expert therein.

Exercise is the first part of the military art, and from it the greatest advantage may be expected, in the expertness with which men become capable of loading and firing, and their learning and attention to act in conformity with those around them. It is not from numbers, or from inconsiderate valour, that victory can rationally be hoped for. In battle the triumph is usually derived from a knowledge of arms, and a strict attention to discipline.

EXERCISE of the infantry, includes the use of the firelock and practice of the manœuvres for regiments of foot, according to regulations used by authority. The beauty of all exercise and marching consists in seeing a soldier carry his arms well, keep his firelock steady, and the whole body without constraint. Every motion should be performed with life, and with the greatest regard to exactness, and in order to these, a regiment should never be under arms longer than two hours at a time.

EXERCISE of the cavalry, is of two sorts, viz. on horseback and on foot. The officers commanding squadrons must be careful to form with great celerity, and preserve just order and distances. The men must keep a steady seat upon their horses, and have their stirrups of a fit length.

EXERCISE of the artillery, is the method of teaching the regiments of artillery the use and practice of all the various machines of war, viz. Exercise of the light field

pieces teaches the men to load, ram, and sponge the guns well; to elevate them according to the distance, by the quadrant and screw; to judge of distances and elevations without the quadrant; how to use, the port-fire, match, and tubes for quick firing; how to fix the drag-ropes, and use them in advancing, retreating, and wheeling with the field-pieces; how to fix and unfix the trail of the carriage on the limbers, and how to fix and unfix the boxes for grapeshot on the carriages of each piece.

EXERCISE of the garrison and battering artillery, is to teach the men how to load, ram, and sponge; how to handle the handspikes in elevating and depressing the metal to given distances, and for ricochet; how to adjust the coins, and work the gun to its proper place; and how to point and fire with exactness, &c.

EXERCISE for the mortar, is of two dif ferent sorts, viz. with powder and shells unloaded, and with powder and shells loaded; each of which is to teach the men their duty, and to make them handy in using the implements for loading, pointing, traversing, and firing, &c.

EXERCISE of the howitzer, differs but little from the mortar, except that it is liable to various elevations; whereas that of the mortar is fixed to an angle of 45o; but the men should be taught the method of ricochet-firing, and how to practice with grape-shot; each method requiring a particular degree of elevation.

EXERCISES are also understood of what young gentlemen or cadets learn in the military academies and riding-schools; such as fencing, dancing, riding, the manual exercise, &c. The late establishment at High Wycomb is calculated to render young officers perfectly competent to all the duties of military service, provided they have been previously instructed in the first rudiments. Officers are there taught and exercised in the higher branches of tactics and man

œuvres.

EXERGUM, among antiquarians, a little space around or without the figures of a medal, left for the inscription, cypher, device, date, &c.

EXHALATION, a general term for all the effluvia or steams raised from the surface of the earth in form of vapour. Some distinguish exhalations from vapours, expressing by the former all steams emitted from solid bodies, and by the latter the steams raised from water and other fluids.

EXHAUSTED receiver, a glass, or other