(Peter), an eminent mathematician and mechanical philosopher, was born at Croisic, in Lower Bretagne, on the 16th of February 1702. His father John Bouguer, who was likewise a considerable mathe-

matician, was then professor royal of hydrography at Bouguer, that port; and under him young Bouguer studied mathematics, and the application of them to ship-building, almost from the period when he began to speak; so that he was a proficient in these sciences before he had reached beyond the years of childhood. He was, however, removed from Croisic to the Jesuits college at Nantes, where, at 13 years of age, he triumphed, in a public contest, over a professor of mathematics, who had advanced a mathematical proposition erroneously. Two years after this he lost his father, whom he was appointed to succeed in the office of hydrographer, after being publicly examined, and giving the most complete proof of his being duly qualified to fill the vacant chair. He was indeed qualified by prudence as well as by science; for however surprising it may be, he filled it both with dignity and with abilities, though then not more than 15 years of age.

In the years 1727, 1729, and 1731, he gained the prizes successively proposed by the Academy of Sciences for essays on the best way of equipping ships with sails, on the best method of observing at sea the height of the stars, and on the most advantageous way of observing the declination of the magnetic needle or the variation of the compass. In 1729 he published an Optical Essay upon the Gradation of Light, in which he examined the intensity of light, and determined its degrees of diminution in passing through different pellucid mediums, and particularly in traversing the earth's atmosphere. Of this essay, which was written upon a subject that till then had not attracted the attention of philosophers, the reader will find some account in the Encyclopedia Britannica, under the title Optics, n° 32, &c.

In 1730 Bouguer was removed from the port of Croisic to that of Havre. In 1731 he obtained, in the Academy of Sciences, the place of associate-geometrician, vacant by the promotion of Maupertuis to that of pensioner; and in 1735 he was promoted to the office of pensioner-astronomer. The same year he was sent on the commission to South America, along with M. de Godin, Condamin, and Jeuffeu, to determine the measure of the degrees of the meridian, and the figure of the earth. In this painful and troublesome business of ten years duration, chiefly among the lofty Cordelier mountains, our author, besides attending to the object of the voyage, made many scientific observations, viz. on the effect of the Cordeliers on the polarity of the magnetic needle; on the expansion and contraction of metals and other substances, by the sudden and alternate changes of heat and cold among those mountains; and on the refraction of the atmosphere from the tops of the same, with the singular phenomenon of the sudden increase of refraction, when the star can be observed below the line of the level. He likewise ascertained the laws of the density of the air at different heights, from observations made at different points of those enormous mountains; he discovered that the mountains have an effect upon a plummet, though he did not assign the quantity of that effect; he found out a method of estimating the errors committed by navigators in determining their route; gave a new construction of the log for measuring a ship's way; and made several other useful improvements. M. Bouguer made at different times some important experiments on the famous reciproca-

tion of the pendulum; he invented in 1747 the helio-

meter. Bouguer (see that article Encycl.) and made many discoveries relating to the intensity of light (for which see Optics Index, Encycl.). His unremitting application to study undermined his health, and he died on the 15th of August 1788, in the 61st year of his age.

Of his works which have been published, the chief are:

1. The Figure of the Earth, determined by the Observations made in South America, 1749, in 4to. 2. Treatise on Navigation and Pilotage, Paris, 1752, in 4to. This work has been abridged by M. La Caille, in one volume 8vo, 1768. 3. Treatise on Ships, their Construction and Motions, in 4to, 1756. 4. Optical Treatise on the Gradation of Light, first in 1729, then a new edition in 1760, in 4to.

His papers that were inserted in the Memoirs of the Academy are very numerous and important; as, in the Memoirs for 1726, comparison of the force of the solar and lunar light with that of candles; 1731, observations on the curvilinear motion of bodies in mediums; 1732, upon the new curves called the lines of pursuit; 1733, to determine the species of conoid, to be constructed upon a given base which is exposed to the shock of a fluid, so that the impulse may be the least possible; determination of the orbit of comets; 1734, comparison of the two laws which the earth and the other planets must observe in the figure which gravity causes them to take; on the curve lines proper to form the arches in domes; 1735, observations on the equinoxes; on the length of the pendulum; 1736, on the length of the pendulum in the torrid zone; on the manner of determining the figure of the earth by the measure of the degrees of latitude and longitude; 1739, on the astronomical refractions in the torrid zone; observations on the lunar eclipse of the 8th September 1737, made at Quito; 1744, short account of the voyage to Peru by the members of the Royal Academy of Sciences, to measure the degrees of the meridian near the equator, and from thence to determine the figure of the earth; 1745, experiments made at Quito and divers other places in the torrid zone, on the expansion and contraction of metals by heat and cold; on the problem of the mailing of ships; 1746, treatise on ships, their structure and motions; on the impulse of fluids upon the fore parts of pyramidaloids, having their base a trapezium; continuation of the short account given in 1744 of the voyage to Peru for measuring the earth; 1747, on a new construction of the log, and other instruments for measuring the run of a ship; 1748, of the diameters of the larger planets; the new instrument called a heliometer, proper for determining them, with observations of the sun; observation of the eclipse of the moon the 8th of August 1748; 1749, second memoir on astronomical refractions, observed in the torrid zone, with remarks on the manner of constructing the tables of them; figure of the earth determined by MM. Bouguer and Condamin, with an abridgment of the expedition to Peru; 1750, observation of the lunar eclipse of the 13th December 1750; 1751, on the form of bodies most proper to turn about themselves, when they are pushed by one of their extremities, or any other point; on the moon's parallax, with the estimation of the changes caused in the parallaxes by the figure of the earth; observation of the lunar eclipse the 2d of December 1751; 1752, on the operations made by seamen, called corrections; 1753, observation of the passage of Mercury over the sun the 6th of May 1753; on the dilatations of the air in the atmosphere; new treatise of navigation, containing the theory and practice of piloting, or working of ships; 1754, operations, &c. for distinguishing, among the different determinations of the degree of the meridian near Paris, that which ought to be preferred; on the direction which the string of a plummet takes; solution of the chief problems in the working of ships; 1755, on the apparent magnitude of objects; second memoir on the chief problems in the working of ships; 1757, account of the treatise on the working of ships; on the means of measuring the light.

BREAD is so essential an article of food that every useful method of making it should be generally known. Much has accordingly been said on that subject (Encycl.) under the titles Baking, Barm, Bread, and Yeast; but, since the last of these articles was published, we have seen, in Dr Townson's Travels in Hungary, a method of making bread at Debreczen; of which, as it may sometimes be adopted with advantage in this country, an account may, with propriety, be inserted here.

In the baking of this bread, a substitute is used for yeast, which is thus made: Two good handfuls of hops are boiled in four quarts of water: this is poured upon as much wheaten bran as can be well moistened by it: to this are added four or five pounds of leaven; when this is only warm, the mass is well worked together to mix the different parts. This mass is then put in a warm place for 24 hours; and after that it is divided into small pieces, about the size of a hen's egg, or a small orange, which are dried by being placed upon a board, and exposed to a dry air, but not to the sun; when dry, they are laid by for use, and may be kept half a year. This is the ferment; and it may be used in the following manner: For a baking of fix large loaves, fix good handfuls of these balls, broken into fragments, are taken and dissolved in seven or eight quarts of warm water. This is poured through a sieve into one end of the bread trough, and three quarts more of warm water are poured through the sieve after it, and what remains in the sieve is well pressed out. This liquor is mixed up with so much flour as to form a mass of the size of a large loaf: this is trewled over with flour; the sieve, with its contents, is put upon it, and then the whole is covered up warm, and left till it has risen enough, and its surface has begun to crack: this forms the leaven. Then 15 quarts of warm water, in which fix handfuls of salt have been dissolved, are poured through the sieve upon it, and the necessary quantity of flour is added, and mixed and kneaded with the leaven: this is covered up warm, and left for about an hour. It is then formed into loaves, which are kept in a warm room half an hour; and after that they are put in the oven, where they remain two or three hours, according to the size. The great advantage of this ferment is, that it may be made in great quantities at a time, and kept for use. Might it not on this account be useful on board of ships, and likewise for armies when in the field?

Bread, in whatever way it is made, is a dear article; and it may be a desirable object to many of our readers to know at what price the baker can afford to sell it. This depends upon the price of wheat, the quantity of flour which the wheat may give, the lois at the mill, the expense of grinding, and the expense of baking. Of the price of wheat we can say nothing with precision, because it varies according to the goodness or badness of the crop, and other circumstances; but a bushel of Essex wheat, Winchester measure, may be taken, on an average, as weighing 60 lb. Sixty pounds of wheat will yield, exclusive of the loss in grinding and dressing, 45½ lb. of that kind of flour which is called seconds; which alone is used, through the greatest part of England, for bread, and which makes, indeed, the best of all bread, though not the whitest. A peck of this flour, weighing 14 lb., will take up between six and seven pints of water, and give 18 lb. of excellent bread; or a bushel of flour, weighing 60 lb., will yield 72 lb. of bread. The expense of baking a bushel of such flour is, in Essex and some other English counties, about ninepence; viz. yeast, on an average, twopence; salt, before the late tax, one halfpenny; and baking, sixpence.

But seconds is not all that is got from wheat. A bushel of 60 lb. of wheat gives, besides 45½ lb. of seconds, 13 lb. of offal, i.e. of pollards and bran; for the utmost loss in grinding and dressing a bushel of wheat should not exceed 1 pound 8 ounces. The millers, indeed, usually reckon on two pounds of loss; but we can say, with the utmost confidence, that the actual loss is rather less than we have stated it. A correspondent of ours, on whose accuracy we can depend, weighed, in 1795, two bushels, Winchester measure, the one of white and the other of red wheat, and found the weight of them both to be 122 lb. This wheat was ground by his own servants, and it yielded 121½ pounds of meal, so that there was here but ½ lb. lost of two bushels, or of 122 lb. in grinding. He admits that he suffered the stones to turn too close, and that the loss should therefore have been somewhat greater. The meal was dressed, as the wheat had been ground, under his own eye; and every possible precaution being taken to prevent his being deceived in the result, he had of flour, or seconds, 93½ lb. and of bran and pollard 25½ lb.; so that he lost, of two bushels, but 2½ lb. both in grinding and dressing. The offal, or bran and pollard, being dressed in a bolting mill, yielded as follows:

| Sharps | 6 lb. 0 oz. | |--------|------------| | Fine pollard | 5 8 | | Coarse pollard | 7 8 | | Broad bran | 5 8 |

Altogether 24 8

There was lost, therefore, in bolting, only one pound; and of the sharps, about three pounds, if fitted, would have been good flour. Indeed were the sharps and fine pollard to be added to the flour, the bread would, perhaps, be better, and more wholesome, than without such addition. From these data, which we believe to be very accurate, it will be easy to calculate, if the price of wheat be given, what should be the price of flour per bushel and peck, the price of bread per pound, and the quantity of bread that should be sold for a shilling.

It is a fact, however, which should be attended to, that loaves are not always of the same weight, though made of equal quantities of the very same dough. This was fully ascertained some years ago at Paris. On a violent complaint that the bread was not always of the same standard weight, the bakers of the city were called before the police officers. They admitted the fact, that loaves, baked at the same time, and in the same oven, were seldom, if ever, of the same weight; but, they insisted, that they contained, each, the standard quantity of dough, and that the variety of weight among them must proceed from some cause, which they did not pretend to ascertain. The matter was referred to the Royal Academy of Sciences, which appointed one of its members to superintend, for some days, the whole process of baking. This being done, it was found, that, of loaves baked in a large oven, those were always heaviest which occupied the centre of the oven, and that the bakers were innocent of the crime with which they were charged. The fact, we think, may easily be accounted for. Even in an oven there must be some condensation of steam; and, from the very shape of the oven, the greatest quantity must be condensed towards the centre. Hence the loaves in the centre are necessarily wetter and heavier than those round the circumference, if the plain of the oven has been equally heated.

Bread of Rice might occasionally be of great use in many countries during a scarcity of wheat; but the method of making it is not generally known. It is indeed impossible to make bread of the flour of rice, which is harsh and dry like sand or ashes, by treating it in the manner in which wheat-flour is commonly treated; and therefore it has been proposed to mix it with an equal quantity of the flour of rye. But this method of using the flour of rice is a very uncertain remedy in case of want; since we can have no rice-bread if we have not rye. We are taught, however, in the Journal des Sciences, des Lettres, et des Arts, how to make excellent bread from rice alone, by a method which the author of the memoir says he learned from the natives of America.

According to this method of making the wildest-for bread, the first thing to be done to the rice is, to reduce it to flour, by grinding it in a mill, or, if we have not a mill, it may be done in the following manner: Let a certain quantity of water be heated in a saucepan or caldron; when the water is near boiling, let the rice we mean to reduce into flour be thrown into it; the vessel is then to be taken off the fire, and the rice left to soak till the next morning. It will then be found at the bottom of the water, which is to be poured off, and the rice put to drain upon a table placed in an inclined position. When it is dry, it must be beat to powder, and passed through the finest sieve that can be procured.

When we have brought the rice into flour, we must take as much of it as may be thought necessary, and put it into the kneading-trough in which bread is generally made. At the same time we must heat some water in a saucepan or other vessel, and, having thrown into it some handfuls of rice, we must let them boil together for some time; the quantity of rice must be such as to render the water very thick and glutinous. When this glutinous matter is a little cooled, it must be poured upon the rice-flour, and the whole must be well kneaded together, adding thereto a little salt, and a proper quantity of leaven. We are then to cover the dough with warm cloths, and to let it stand that it may rise. During the fermentation, this paste (which, when kneaded, must have such a proportion of flour as to render it pretty firm) becomes so soft and liquid that it seems impossible it should be formed into bread.

It is now to be treated as follows:

While the dough is rising, the oven must be heated; and, when it is of a proper degree of heat, we must take a flewpans of tin, or copper tinned, to which is fixed a handle of sufficient length to reach to the end of the oven. A little water must be put into this flewpans, which must then be filled with the fermented paste, and covered with cabbage or any other large leaves, or with a sheet of paper. When this is done, the flewpans is to be put into the oven, and pushed forward to the part where it is intended the bread shall be baked; it must then be quickly turned upside down. The heat of the oven acts upon the paste in such a way as to prevent its spreading, and keeps it in the form the flewpans has given it.

In this manner pure rice-bread may be made; it comes out of the oven of a fine yellow colour, like pastry which has yolk of eggs over it. It is as agreeable to the taste as to the sight; and may be made use of, like wheat-bread, to put into broth, &c. It must, however, be observed, that it loses its goodness very much as it becomes stale.

It may be here remarked, that the manner in which Indian corn is used in some countries, for making bread, can only produce (and does in fact produce) very bad dough, and of course very bad bread. To employ it advantageously, it should be treated like rice; and it may then be used, not only for making bread, but also for pastry.

BREWING is an art of vast importance, and has accordingly been explained in the Encyclopaedia Britannica. A few improvements, however, have been made in the art, which, though not noticed in that Work, seem to be worthy of general attention, and, therefore, to deserve a place in this Supplement. The first, of which we shall give an account, is an invention of Mr William Ker of Kerfield, in the county of Tweedale, for the saving of hops, and, at the same time, giving to the liquor, whether ale, beer, or porter, a superior flavour and quality.

The steam which arises from the boiling copper is known to be strongly impregnated with the essential oil of the hops, in which their flavour consists. Instead, therefore, of allowing it to escape and evaporate, as it does in the common mode of brewing, Mr Ker contrives to preserve and condense it, by means of a winding pipe fixed to the copper, similar to the worm of a still, or by a straight pipe passing through cold water, or any other cooling medium. The oil and water, thus obtained, are returned into the worts when boiled, or the oil, after being separated from the water, along with which it had been exhaled, is returned into the worts after they are boiled; and the watery part, which, after the oil is separated, still continues impregnated with the aromatic taste and bitter of the hop, is returned into the next copper or boiling-vessel; and so on from one copper or boiling-vessel into another. By this process a considerable part of the hop and flavour, which is lost in the ordinary mode of brewing, is preserved; the flavour of the liquor is improved by the preservation of the finer parts of the aromatic oil; and the ale and beer are better freed from any tendency to acidity or putrefaction, and therefore, must be fitter for home consumption and exportation. For this invention, which is certainly simple, and we think rational, Mr Ker obtained a patent, dated March 4, 1788.

On the 4th of June 1790, Mr John Long of Longville, in the county of Dublin, Ireland, obtained a patent for an improvement in brewing, resembling, in one particular, this invention of Mr Ker's. To his invention, however, he gives the name of an entire new method, in all the essential parts, of brewing good malt-liquor; and therefore, as it comprehends the whole process of brewing, we shall lay it before our readers in the words of its author:

"1. For the better extracting from malt, place near a mash-tun a shallow copper or other vessel that will readily heat; the curb of which to be on a level with the tun, and to contain from two to six hogsheads, according to the dimension of the tun, more or less; and, at the lower end of the copper, have a cock from two to five inches diameter, more or less, to conduct the heated liquor from the copper into a tube which passes down the external part of the tun, and enters it through an aperture about six inches from the bottom; then forming two revolutions, more or less, through the body of the tun, and communicating its heat to the wort as it passes through the tube; and then, at a convenient distance from the place it first entered, it runs from the tun into a cistern or tub, situate as near as convenient to the copper or heating vessel. In the tub or cistern is to be placed a pump, for the purpose of conveying the cooler liquor back to the copper or heating-vessel again; there to receive the heat of 203 degrees, more or less (which it will require after the first half hour), and then convey it through the mashing-tun as before, and in the same manner, as long as the working brewer or distiller may think necessary, to raise the mashing-tun to any degree of heat required. By adhering to the foregoing process, the first liquor may, with the greatest safety, be let upon the malt from 20 to 30 degrees lower than the present practice; by which means it operates with gentleness, opens and expands the malt and raw corn, and prepares it for the reception of sharper or warmer liquor, so as to extract the whole of the saccharine quality from the malt and raw corn. By the foregoing method, the mashing-tun, instead of losing its first heat (which it does by the present practice), continues to increase in heat every moment, by conveying the heated liquor through the tube into the tun; by which means, at the end of two hours, the working brewer or distiller can have the tun brought to any degree of heat he shall think best suited to the different qualities of the malt or raw corn. Persons who would wish to save expense, may heat their mashing-tun at the side or bottom by a large piece of metallic substance made fire-proof, and fixed therein; which, in some degree, will answer the end proposed, but with great trouble and delay.

"2. To prevent the wort from receiving a disagreeable flavour while in the under-back; a tube must be placed at the cock of the mashing-tun, to receive the wort as it comes off, and convey it to a great cistern or refrigeratory, which is supplied with a stream of water. The wort, passing through that medium in a spiral tube, soon loses that heat which so often proves prejudicial to the brewer and distiller in warm weather; then pass it from the tube into a vessel in which pumps are..." Brewing are placed, to return the worts into the copper for the purpose of boiling off. All vessels for receiving the cold wort must be placed lower than the source whence the wort comes.

"3. As the great object of long boiling the wort is remedied, by my invention of taking the extract from the hops in a separate manner from the worts, I boil my worts no longer than from 15 to 20 minutes; and, by pursuing that method, I save much time and fuel, and regulate my lengths accordingly.

"4. I steep my hops, the preceding day to which they are to be used, in a copper or other vessel, with as much fluid, blood-warm, as will cover the hops, where it is to remain over a slow fire at least 14 hours; close covered; the copper at the tenth hour not to be of a greater heat than 175 degrees, continuing slow until the last hour. Then I bring the copper gradually to a simmer or slow boil; in which state I let it remain about 10 minutes, and then run off the fluid; and this I do at the same time the first wort is boiled off, that they may both pass together through the refrigeratory into the fermentation or working-tun. After the foregoing operation, I cover the hops again with other liquor, and bring the copper to boil as soon as convenient, and let it remain in that state a considerable time, until the second worts are boiled off. Then I pass the hop-fluid with the wort, the same as in the first instance; and, if there is a third wort, I boil my hops a third time with small worts, and pass it off as before; by which means I gradually obtain the whole of the essential oil and pleasing bitter from the hops, which is effectually preserved in the beer.

"5. To cool worts. When the wort is boiled off, it is conducted from the cock of the copper or boiler into a tube of a proper dimension, which passes the wort from the cock to the large cistern or refrigeratory, and there performs several revolutions, in a spiral manner, through the same tube; which is immersed in constant supply of cold water, where it loses the greatest part of its heat in a short time, and thence continues a straight course through the tube, a little elevated and of a suitable length, placed in brick-work, until it meets a small refrigeratory, supplied with colder water from a reservoir made for that purpose at the head of the works; whence a continual stream runs on the surface of the tube down to the great refrigeratory, cooling the wort as it passes, in order to enable the working brewer or distiller to feed it into the backs or working-tuns at whatever degree of heat he shall think proper. There is no other difference between brewer and distiller in this process, but that the distiller immediately passes the strong wort from the mashing-tun to the back, through the same machinery above inserted, and the tubes may be made of lead, or any other metallic substance.

"6. To enable me to brew in the warm summer months, I sink my backs or working-tuns at least to a level with the ground, but if deeper the better, and cover them closely by an arch made of bricks, or other materials, that will totally exclude the atmospheric air from them. I place them as near as possible to a spring or sand-drain, as their depth will naturally draw the water thence, which must be so contrived as to pass or flow round the backs or tuns. I then introduce a large tube, which passes through the tuns, and keeps the wort several degrees lower than can possibly be done by the present practice; by which means I can produce a complete fermentation even in the dog-days.

"7. In cold or frosty weather, if the tun and backs should lose the first heat, intended to carry it through the process by the foregoing method, you may convey a supply of warm or boiling water by the tube, which passes through the body of the backs or tun, communicating its heat, which rises to any degree the working brewer shall think proper; by pursuing this method, in the coldest season, I never want a fermentation."

We regret that we cannot with propriety state to our readers, under this article, a summary of Mr Richardson of Hull's Philosophical Principles of Brewing; for as the author has a new edition of his work in the press, it is our duty rather to refer to it, than to quote from a former edition, which contains not his last improvements. See Fermentation and Malt, in this Supplement.