Lock, waves. But inviolable security is not the only excel Locke. lence they possess; the simplicity of their principle gives them likewise a great advantage over locks that are more complicated, in point of duration; for their essential parts being subject to no friction, nor exposed to any possible accident from without, they will be less affected by use, and less liable to stand in need of repair."

LOCK, or Weir, in inland navigations, the general name for all those works of wood or stone made to confine and raise the water of a river: the banks also which are made to divert the course of a river, are called by these names in some places. But the term lock is more particularly appropriated to express a kind of canal enclosed between two gates; the upper called by work men the sluice gate, and the lower called the flood gate. These serve in artificial navigations to confine the water, and render the passage of boats easy in passing up and down the stream. See CANAL.

LOCKE, JOHN, an eminent English philosopher and writer in the latter end of the 17th century, was son of Mr John Locke of Pensford in Somersetshire, and born at Wrington, near Bristol, in 1632. He was sent to Christ-church in Oxford; but was highly dissatisfied with the common course of studies then pursued in the university, where nothing was taught but the Aristotelian philosophy; and had a great aversion to the disputes of the schools then in use. The first books which gave him a relish for philosophy were the writings of Des Cartes: for though he did not always approve of his notions, yet he thought he wrote with great perspicuity. He applied himself with vigour to his studies, particularly to physic, in which he gained a considerable knowledge, though he never practised it. In 1664, he went to Germany as seeretary to Sir William Swan, envoy from the English court to the elector of Brandenburg and some other German princes. In less than a year, he returned to England; where, among other studies, he applied himself to that of natural philosophy, as appears from a register of the changes of the air, which he kept at Oxford from June 24. 1666, to March 28. 1667. There he became acquainted with the lord Ashly, afterwards earl of Shaftesbury, who introduced him into the conversation of some of the most eminent persons of that time. In 1670, he began to form the plan of his Essay on Human Understanding; but his employments and avocations prevented him from finish ing it then. About this time he became a member of the Royal Society. In 1672, his patron, now earl of Shaftesbury, and lord chancellor of England, appointed him secretary of the presentations, which place he held till the earl resigned the great seal. In 1673, he was made secretary to a commission of trade, worth gool. a-year; but that commission was dissolved in 1674. The earl of Shaftesbury being restored to favour, and made president of the council in 1679, sent for Mr Locke to London: but that nobleman did not continue long in his post, being sent prisoner to the Tower; and after his discharge retired to Holland in 7682.

Mr Locke followed his patron thither. He had not been absent from England a year, when he was ac eused at court of having written certain tracts against the government, which were afterward discovered to be

written by another person; and in November 1684, Locke he was deprived of his place of student in Christchurch. In 1685, the English envoy at the Hague Locle. demanded him and 83 other persons to be delivered up by the states general: upon which he lay concealed till the year following; and during this time formed a weekly assembly with Mr Limborch, Mr Le Clerc, and other learned men at Amsterdam. In 1689 he returned to England in the fleet which conveyed the princess of Orange; and endeavoured to procure his restoration to his place of student of Christ-church, that it might appear from thence that he had been unjustly deprived of it: but when he found the college would admit him only as a supernumerary student, be desisted from his claim.

Being esteemed a sufferer for revolution principles, he might easily have obtained a more profitable post; but he contented himself with that of commissioner of appeals, worth 200l. a-year, which was procured for him by the lord Mordaunt; and about the same time he was offered an appointment in a diplomatic character, but the infirm state of his health prevented him from accepting it. He went afterwards to reside with Sir Francis Masham and his lady, at Oates in Essex, about 25 miles from London, where he spent most of his time during the rest of his life. In this agreeable situation he enjoyed that health and vigour which enabled him to exert his talents in writing on political subjects. Hence he appears in defence of the revolution in one piece; and considering the great national concern at that time, the ill state of the silver coin, and proposing remedies for it, in others. Hence he was made a commissioner of trade and plantations in 1695, which engaged him in the immediate business of the state; and with regard to the church, he published a treatise the same year, to promote the scheme which King William had much at heart, of a comprehension with the dissenters. This, however, drew him into one controversy; which was scarcely ended, when he entered into another in defence of his essay, which he held till 1698;. soon after which the asthma, his constitutional disorder, increasing with his years, began to subdue him; and he became so infirm, that in 1700 he resigned his seat at the board of trade, because he could no longer bear the air of London sufficient for a regular attendance upon it. After this resignation he continued altogether at Oates; in which retirement he employed the remaining last years of his life entirely in the study of the Holy Scriptures.

He died in 1704, aged 73. His writings will immortalize his name. The earl of Shaftesbury, author of the Characteristics, though in one place he speaks of Mr Locke's philosophy with severity; yet observes, concerning his Essay on the Human Understanding, in general, "that it may qualify men as well for business and the world, as for the sciences and the university." His Discourses on Government, Letters on Toleration, and Commentaries on some of St Paul's Epistles, are also held in much esteem.

LOCKED JAW. See MEDICINE Index. LOCKMAN, an officer in the isle of Man, who executes the orders of government, much like our under sheriff.

LOCKMAN, an eastern philosopher. See LOKMAN.
LOCLE, a town in a district of the same name

in Switzerland, adjacent to Neufchatel and Vallengin, and united with another named La Ghaux de Fond. But these districts occupy some valleys formed by the mountains of Jura; the greatest part of which not many years ago was one continued forest, though now converted into fine pasture ground filled with flourishing villages. The inhabitants are remarkable for their industry, and excel in many mechanical arts, particularly in watch and clock making; 40,000 watches, it is said, are made in a year. The most singular object at this place, is three subterranean mills, crected on the river Bied, vertically above one another, and 100 feet below the surface of the ground.

LOCRI, or LOCRI Epizephyrii, in Ancient Geography, a town on the Ionian sea near the promontory Zephyrium. The people are said to be the first ho used a code of written laws, compiled by Zaleucus from the laws of the Cretans and others.

LOCRIS, a country of Achaia in Greece; twofold, and divided by Mount Parnassus. The Hither was occupied by the Locri Ozola, called also Zephyriï, or Western, contained between Ætolia and Phocis. The Farther Locris lay beyond Parnassus, running out towards Thermopyle, and reaching to the Euripus of Euboea; occupied by the Locri Opuntii, and Epicne midii, who were called the Eastern Locri.

LOCUS GEOMETRICUS, denotes a line by which a local or indeterminate problem is solved.

A locus is a line, any point of which may equally solve an indeterminate problem. Thus if a right line suffice for the construction of the equation, it is called locus ad rectum; if a circle, locus ad circulum; if a parabola, locus ad parabolam; if an ellipsis, locus ad ellipsin: and so of the rest of the conic sections.

LOCULAMENTA, and LOCULI, in Botany, cells or pockets: The internal divisions of a capsule, or other dry seed-vessel, enclosing the seeds.

LOCUST. See GRYLLUS, ENTOMOLOGY Index. LOCUST-Eaters. See ACRIDOPHAGI. American LocUST, or Frog-hopper. See CICADA, ENTOMOLOGY Index.

LOCUST-Tree. See HYMENEA and GLEDITSIA, BoTANY Index.

LOCUTIUS, in Mythology, the god of speech among the Romans, called by Livy Anis Locutius.

LUCUTORIUM. A hall or apartment in monasteries, where the monks and other religious met after dinner to converse together.

LODI, a walled town of Austrian Lombardy, situated on the Adda, in 45. 20. N. Lat. and 9. 30. E. Long. It has a cathedral, 9 churches, and 26 convents, and about 12,000 inhabitants. Here Bonaparte defeated the Austrians in 1796.

LODGMENT, in military affairs, a work made by the besiegers in some part of a fortification (after the besieged have been driven out), to maintain it, and be covered from the enemy's fire.

LOG, in the Jewish antiquities, a measure which held a quarter of a cab, and consequently five-sixths of a pint. There is mention of a log, 2 Kings vi. 25. under the name of a fourth part of a cab. But in Leviticus the word log is often met with, and signifies. the measure of oil which lepers were to offer at the temple after they were cured of their disease. Dr Arbuthnot says, that the log was a measure of liquids, the seventy-second part of the bath or ephah, and 4

twelfth part of the hin, according to all the accounts of Leg the Jewish writers.

CCXVII. fig. 3.

LOG, a sea term, signifying a small piece of timber Plate (fig. 3.) of a triangular, sectoral, or quadrantal figure, on board a ship, generally about a quarter of an inch thick, and five or six inches from the augular point to the circumference. It is balanced by a thin plate of lead, nailed to the arch, or circular side, so as to swin perpendicularly in the water..

Loa-Line, a little cord, or line, about a hundred and fifty fathoms long, fastened to the log by means of two legs ab (fig. 4.), one of which passes through a hole Fig. 4. at the corner, and is knotted on the opposite side, while the other leg is attached to the arch by a pin fixed into another hole, so as to draw out occasionally. By these legs the log is hung in equilibrio; and the line thus annexed to it is wound round a reel (fig. 2.), fixed for Fig. zz that purpose in the gallery of the ship.

This line, from the distance of about ten, twelve, or fifteen fathoms off the log, has certain knots or divisions, which ought to be at least fifty feet from each other; though it was the common practice at sea not to have them above forty-two feet asunder.

of

The length of each knot ought to be the same part of a sea mile as half a minute is of an hour; and admitting the measurement of Mr Norwood, who makes a degree on a great circle of the earth to contain 367,200 English feet, or about 69% English statute miles, and therefore th part of it, er a nautical mile, will be 6120 feet; th of 6120, or 51 feet, should be the length of each knot. But because it is safer to have the reckoning rather before the ship than after it, therefore fifty feet may be taken as the proper length of each knot. The knots are sometimes made to consist only of forty-two feet each, even in the present practice; and this method of dividing the logline was founded on the supposition that 60 miles, each of 5000 English feet, made a degree; for 5000 is 41, or, in round numbers, 42 feet. Mariners rather than quit the old way, though known to be erroneous, use glasses for half minute ones, that run but 24 or 25 seconds. They have also used a line of 45 feet or 30 seconds, or a glass of 28 seconds to 42 feet. When this is the case, the distance between the knots should be corrected by the following pro-. portion: as 30 is to 50; so is the number of seconds of the glass to the distance between the knots upon the line. The heat or moisture of the weather has often a considerable effect upon the glass, so as to make it run slower or faster; it should, therefore, be frequently tried by the pendulum in the following manOn a round nail hang a string that has a musket ball fixed to one end, carefully measuring between the centre of the ball and the string's loop over the peg 39 inches, being the length of a second pendulum; then swing it, and count one for every time it passes under the peg, beginning at the second time it passes, and the number of swings made during the time the glass is running out shows the seconds it contains. The line also is liable to relax and shrink, and should therefore be occasionally measured.

ner.

The use of the log and line is to keep account and make an estimate of the ship's way or distance run;which is done by observing the length of line unwound in half a minute's time, told by a half-minute glass; for so many knots as run out in that time, so many

miles.

Log.

miles the ship sails in an hour. Thus, if there be four knots veered out in half a minute, the ship is computed to run four miles an hour.

The author of this device for measuring the ship's way is not known; and no mention of it occurs till the year 1607, in an East India voyage published by Purchas; but from that time its name occurs in other voyages among his collections; and henceforward it was taken notice of both by our own authors and by foreigners; as by Gunter in 1623; Snellius in 1624; and almost by all the succeeding writers on navigation.

To Heave the LOG, as they call it, they throw it into the water on the lee-side, letting it run till it comes without the eddy of the ship's wake; then one holding a half minute glass, turns it up just as the first knot, or the mark from which the knots begin to be reckonPig. 2. ed, turns off the reel (fig. 2.) or passes over the stern. As soon as the glass is out, the reel is stopped, and the knots run off are told, and their parts estimated.

It is usual to heave the log once every hour in ships of war and East Indiamen, and in all other vessels once in two hours, allowance being made for the wind having increased or abated in the intervals.

The log is a very precarious way of computing, and must always be corrected by experience, there being much uncertainty from the motions of the ship, the winds of variable force, the friction of the reel and lightness of the log in the course of the current. Yet this is a much more exact way of computing than any other in use; much preferable certainly to that of the Spaniards and Portuguese, who guessed at the ship's way by the running of the froth or water by the ship's side; or to that of the Dutch, who used to heave a chip overboard, and to number the paces they walk on the deck while the chip swims between any two marks or bulk heads on the side.

Compound LoG. The above-mentioned errors, and particularly the log's being subject to drive with the motion of the water at its surface, whereas the experiment requires it to be fixed in the place where it is when the mark commencing the knots goes off the reel, have been considered, and many methods proposed to remove or to lessen them. M. Bouguer proposed the Mem Acad following method. Take for the log a conical piece of Scun. 1747 wood, which fix to the log-line passed through or along its axis, at about 40, 50, or 60, or more feet, from one end; and to this end fix the diver, which is a body formed of two equal square pieces of tin, or of thin iron plate, fixed at right angles to one another along their diagonals; and its size so fitted to that of the cone, that the whole may float. A cone of three inches diameter in the base, and of six inches in the slant height, is proposed by M. Bouguer to suit a diver made of plates about 9 inches square; the intersection of the diagonals is joined to the log-line, and the loop and peg fixed as in the common log. However, it has been found, that no kind of wood used in British dockyards, when formed into a cone of the above dimensions, will float a diver made of stout tin-plates, one side of the square being 9 inches. Such a diver weighing 13lb. avoirdupois, required to float it a cone of five inches diameter and twelve inches on the slant side, so as the point of the cone, which was made of light fir, should just appear above the water. Now, supposing sone side of such a square tin diver to be about ten inches,

3

and made of plates only two-thirds of the thickness of the former, such a diver would weigh, with its solder, about 20 ounces, and can be floated by a light fir cone of four inches diameter in the base, and ten inches in the slant height or length; and such a compound log might perhaps be found on trial to be affected by about as much again as that proposed by M. Bouguer; and consequently the difference between the numbers given by the common log and compound log, must be augmented by two-thirds of itself for the necessary correction as below. When the compound log of Bouguer, above described, is hove overboard, the diver will sink too deep to be much affected by the current or motion of water at the surface, and the log will thereby keep more steadily in the place where it first fell and consequently the knots run off the reel will show more accurately the ship's rate of sailing. As the common log is affected by the whole motion of the current, so this compound log will feel only a part thereof, viz. such a part nearly as the resistance of the cone is to the resistance of the diver; then the resistances of the above cone and diver are about as I to 5; and consequently this log will drive but onefifth part of what the common log would do; and so the ship's true run will be affected by one-fifth only of the motion of the waters. To obtain the true rate of sailing, it will be proper to heave alternately, hour and hour, the common log, and this compound log; then the difference of their knots run off, augmented by its one-fourth part, is the correction; which applied to the knots of the common log, will give the ship's true rate of sailing at the middle time between the hours when these logs were hove. The correction is additive when the compound log's run is the greatest, otherwise it is subtractive. To find the course made good increase the observed angle between the log lines by one-fourth part; and this gives the correction to be applied to the apparent course, or the opposite of that shown by the common log; the correction is to be applied to the right of the apparent course, when the bearing of } left left 7 the common log is to the of the compound right log. Or, thus: the lengths run off both logs, together with their bearings, being known; in a card or compass apply the knots run off, taken from a scale of equal parts along their respective bearings from the centre; join the ends; and in this line produced, on the side next the compound log's length, take onefourth of the interval; then a line drawn from the end, thus produced, to the centre of the card, will show the true course and distance made good. When a current, such as a tide, runs to any depth, the velocity of that current may be much better ascertained by the compound log than by the common one, provided the diver does not descend lower than the run of the current; for as those ships which are deepest immerged, drive fastest with the tide; so the diver, by being acted on below, as well as the log on the surface, their joint motion will give the total effect of the current's motion better than what could be derived from the motion at the surface only. Also, by such a compound log, the depth to which any current runs may be easily tried.

Other LoGs. We have an account in the voyage to the North