elements, the result is an alloy, or proper chemical combination. One of the most striking proofs of actual combination between the parts of an alloy, is a remarkable increase of fusibility. This, in almost all cases, is much greater than could be inferred from the mean fusibility of its component parts. Thus, equal parts of tin and iron will melt at the same temperature as is required for equal parts of tin and copper, notwithstanding the great difference between the fusing heat of copper and iron, when they are each of them pure. So also an alloy of tin, bismuth, and lead, in the proportion of 5, 8, and 5, will melt in boiling water, which is a less heat than is necessary for the liquefaction of bismuth, the most fusible of the three. The oxydability of an alloy is generally either greater or less than that of the unmixed metals. Tin and lead mixed will, at a low red heat, take fire and oxydate immediately.

ALLUSION, in rhetoric, a figure by which something is applied to, or understood of another, on account of some similitude between them.

ALLUVIAL, by alluvial depositions is meant the soil which has been formed by the destruction of mountains, and the washing down of their particles by torrents of water. The alluvial formations constitute the great mass of the earth's surface. They have been formed by the gradual action of rain or river water upon the other formations. They may be divided into two kinds, viz. those deposited in the valleys and mountainous districts, or upon elevated plains, which often occur in mountains; and those deposited upon flat land. The first kind consists of sand, gravel, &c. which constituted the more solid parts of the neighbouring mountains, and which remained when the less solid parts have been washed away. They sometimes contain ores, particularly gold and tin, which existed in the neighbouring mountains. The second kind consists of loam, clay, sand, turf, and calctuff. Here are also earth and brown coal in which amber is found, wood coal, bituminous wood, and bog-iron ore. The sand contains some metals. The calctuff contains plants, roots, moss-bones, &c. which it has incrusted. The clay and sand often contain petrified wood, and skeletons of quadrupeds.

ALLUVION, among civilians, denotes the gradual increase of land along the seashore, or on the banks of rivers. This, when slow and imperceptible, is deemed a lawful means of acquisition; but when a

considerable portion of land is torn away at once by the violence of the current, and joined to a neighbouring estate, it may be claimed again by the former owner.

ALMAGEST, the name of a celebrated book composed by Ptolemy; being a collection of a great number of the observations and problems of the ancients, relating to geometry and astronomy; but especially the latter. And being the first work of this kind which has come down to us, and containing a catalogue of the fixed stars, with their places, beside numerous records and observations of eclipses, the motions of the planets, &c. it will ever be held dear and valuable to the cultivators of astronomy. See PTOLEMY.

In the original Greek it is called συνταξις My, the "great composition" or "collection." And to the word in the Arabians joined the particle "al," and thence called it "Almaghesti," or, as we call it, from them, the Almagest.

ALMAMON, Caliph of Bagdat, a philosopher and astronomer in the beginning of the ninth century, he having ascended the throne in the year 814. He was son of Harun Al-Rashid, and grandson of Almansor. Having been educated with great care, and with a love for the liberal sciences, he applied himself to cultivate and encourage them in his own country. For this purpose he requested the Greek emperors to supply him with such books of philosophy as they had among them; and he collected skilful interpreters to translate them into the Arabic language. He also encouraged his subjects to study them; frequenting the meetings of the learned, and assisting at their exercises and deliberations. He formed a college at Khorasan, and selected to preside over it Mesul of Damascus, a famous Christian physician. When his father, who was still living, remonstrated against the appointment, on account of the president's religion, he replied, that he had chosen him, not as a teacher of theology, but for the instruction of his subjects in science and the useful arts, and that his father well knew, that the most learned men and skilful artists in his dominions were Jews and Christians. He caused Ptolemy's Almagest to be translated in 827, by Isaac Ben-honain, and Thabet Ben-korah, according to Herbelot, but according to others by Sergius, and Alhazen, the son of Joseph. In his reign, and doubtless by his encouragement, an astronomer of Bagdat, named Habash, composed three sets of astronomical tables.

Almamon himself made many astronomical observations, and determined the obliquity of the ecliptic to be then 23° 35', or 23° 33′ in some manuscripts, but Vossius says 23° 51′ or 23° 34'. He also caused skilful observers so procure proper instruments to be made, and to exercise themselves in astronomical observations; which they did accordingly at Shemasi in the province of Bagdat, and upon Mount Casius, near Damas.

Under the auspices of Mamon also a degree of the meridian was measured on the plains of Sinjar, or Sindgiar, upon the borders of the Red Sea; by which the degree was found to contain 563 miles, of 4000 coudees each, the coudee being a foot and a half: but it is not known what foot is here meant, whether the Roman, the Alexandrian, or some other. Abulfeda says that this cubit contained 27 inches, each inch being determined by six grains of barley placed sideways; but Thevenot says, that 144 grains of barley placed in this manner would give a length equal to 14 Paris foot: four cubits would be equal to one toise and nine inches, and therefore 4000 cubits, that is 564 miles, would give 63,730 toises. But if the ordinary cubit of 24 inches was the measure to which the calculation is to be referred, the degree, in this estimate of it, would contain 56,666 toises. According to another valuation of a cubit, this measure would consist of 53,123 French toises.

Almamon was a liberal and zealous encourager of science, in consequence of which the Saracens began to acquire a degree of civilization and refinement to which they had formerly been strangers. The liberality of his mind obtained for Almamon the reputation of infidelity. But whatever opinions he might hold respecting the Koran, he seems to have had a confidence and trust in the Supreme Being. In this work we shall not follow the caliph into the field of battle, nor record his victories, which were brilliant and important. We must look to him in the character of a philosopher and man of science, and in addition to what has already been noticed, we may remark, that he built a new nilometer, for measuring the increase of the Nile, and repaired one that was gone to decay. In the year 833, as he was returning from one of his expeditions, he unwarily quenched his thirst, while very much heated by exerIcise, with cold water, which brought on a disorder that terminated his life. During his last illness, he settled the affairs of the state,

and then exclaiming in the spirit of piety, "O thou who never diest, have mercy on me, a dying man." He expired at the age of 49, after a reign of 20 years. He was interred at Tarsus. To the principles of science, and not to those of the Mohammedan religion, have been ascribed the liberality and benignity of temper which he displayed in certain trying circumstances. When his uncle and rival Ibrahim was taken, brought to trial, and condemned, the caliph, instead of sanctioning the sentence, tenderly embraced his relation, saying, "Uncle, be of good cheer, I will do you no injury:" and he not only pardoned him; but granted him a rank and fortune suitable to his birth. Being complimented on account of this generous deed, he exclaimed," Did but men know the pleasure that I feel in pardoning, all who have offended me would come and confess their faults." Almamon in the course of his reign, employed the most skilful astronomers that he could find to compose a body of astronomical science, which still subsists among oriental MSS. entitled, "Astronomia elaborata à compluribus D.D. jussu regis Maimon."

ALMANAC, in matters of literature, a table containing the calendar of days and months, the rising and setting of the sun, the age of the moon, &c.

Authors are neither agreed about the inventor of almanacs, nor the etymology of the word; some deriving it from the Arabic particle al, and manah, to count; whilst others think it comes from almanah, i. e. handsels, or new year's gifts, because the astrologers of Arabia used, at the beginning of the year, to make presents of their ephemerides for the year ensuing.

As to the antiquity of almanacs, Ducange informs us, that the Egyptian astrologers, long before the Arabians, used the term almenach, and almenachica descriptio, for their monthly predictions. Be this as it will, Regiomontanus is allowed to have been the first who reduced almanacs to their present form.

ALMANACS, construction of. The first thing to be done, is to compute the sun's and moon's place for each day in the year, or it may be taken from some ephemerides and entered in the almanac; next, find the dominical letter, and, by means thereof, distribute the calendar into weeks: then, having computed the time of Easter, by it fix the other moveable feasts; adding the immoveable ones, with the names of the martyrs, the rising and setting of each luminary, the

length of day and night, the aspects of the planets, the phases of the moon, and the sun's entrance into the cardinal points of the eliptic, i. e. the two equinoxes and solstices.

These are the principal contents of almanacs; besides which there are others of a political nature, and consequently different in different countries, as the birth-days and coronation of princes, tables of interest, &c. On the whole, there appears to be no mystery, or even difficulty, in almanac-making, provided tables of the heavenly motions be not wanting. For the duties upon almanaes, see STAMP-DUTIES.

ALMANAC, nautical, and astronomical ephemeris, is a kind of national almanac, published annually by anticipation, under the direction of the commissioners of longitude. Besides every thing essential to general use that is to be found in other almanacs, it contains, among other particulars, the distances of the moon from the sun and fixed stars for every three hours of apparent time, adapted to the meridian of Greenwich, by comparing which with the distances carefully observed at sea, the mariner may readily infer his longitude to a degree of exactness, that may be thought sufficient for most nautical purposes. The publication of it is chiefly designed to facilitate the use of Mayer's lunar tables, by superseding the necessity of intricate calculations in determining the longitude at sea.

was at first intended as a proof of the goodness of the commodity, and therefore a seal was invented as a signal that the commodity was made according to the statute.

ALNAGER, in the English polity, a public sworn officer, whose business is to examine into the assize of all woollen cloth made throughout the kingdom, and to fix seals upon them. Another branch of his office is to collect an almage duty to the king. See the last article.

There are now three officers relating to the alnage, namely, a searcher, measurer, and alnager; all which were formerly comprized in the alnager, until by his own neglect it was thought proper to separate these offices.

ALNUS, the alder-tree, in botany. See BETULA.

ALOE, in botany, a genus of the Hexandria Monogynia class of plants, with a liliaceous flower, consisting of only one tubular leaf, divided into six deep segments at the edge: its fruit is an oblong capsule, divided into three cells, and containing a number of angulated seeds. There are 16 species.

Several species of this exotic plant are cultivated in the gardens of the curious, where they afford a very pleasing variety, as well by the odd shape of their leaves as by the different spots with which they are variegated.

Some aloes are arborescent, or divided into a number of branches, like trees; others are very small, growing close to the ground. The two most considerable species are the aloe of America, and that of Asia; the former on account of its beautiful flowers, and the latter for the drug prepared from it.

DALUS.

ALMUCANTARS, in astronomy, an Arabic word denoting circles of the sphere passing through the centre of the sun, or a star, parallel to the horizon, being the same as parallels of altitude.

Almucantars are the same with respect to the azimuths and horizon, that the parallels of latitude are with regard to the meri. dians and equator. They serve to shew the height of the sun and stars, and are described on many quadrants, &c.

ALNAGE, or AULNAGE, in the English polity, the measuring of woollen manufactures, with an ell, and the other functions of the alnager. See the next article. Alnage

All the aloes are natives of hot climates; and the place of growth of most of them is the Cape of Good Hope. The Hottentots

A. dichotoma, to make quivers for their arrows; and several of them are used for hedges. Among the Mahometans, and particularly in Egypt, the aloe is a kind of symbolic plant, and dedicated to the offices of religion: for pilgrims, on their return from Mecca, suspend it over their doors as an evidence of their having performed that holy journey. The superstitious Egyptians imagine, that it has the virtue of keeping off apparitions and evil spirits from their houses, and it is hung over the doors of Christians and Jews in Cairo for this purpose. They also distil from it a water, which is sold in the shops, and recommended in coughs, asthmas, and hysterics. Hasselquist men

tions a person who was cured of the jaundice in four days by taking about half a pint of it. The Arabians call it sabbara. The negroes, as we are informed by Adanson, in his voyage to Senegal, make very good ropes of the leaves of the Guinea aloes, which are not apt to rot in water. M. Fabroni, as we learn from the Annales de Chimie, procured from the leaves of the aloe succotrina angustifolia a violet dye, which resists the action of oxygen, acids, and alkalies. This juice, he says, produces a superb transparent colour, which is highly proper for works in miniature, and which, when dissolved in water, may serve, either cold or warm, for dying silk from the lightest to the darkest shade: and he reckons it one of the most durable colours known in nature. Aloes was used among the ancients, in embalming, to preserve bodies from putrefaction. Of this species of aloes, interpreters understand that to have been which Nicodemus brought to embalm the body of Christ. John xix. 3. Aloes, whose resinous part is not soluble in water, has been used as a preservative to ships' bottoms against the worms, to which those that trade to the East and West Indies are particularly subject. One ounce of aloes is sufficient for two superficial feet of plank; about 12 lb. for a vessel of 50 tons burthen, and 300 lb. for a first rate man of war. It may be incorporated with six pounds of pitch, one of Spanish brown, or whiting, and a quart of oil; or with the same proportion of turpentine, Spanish brown, and tallow. Such a coat, it has been said, will preserve a ship's bottom eight months, and the expense for a first-rate ship will be about 181. The same composition may be used in hot countries for preserving rafters, &c. from the wood-ant. The efficacy of aloes, as a defence against worms, has been controverted.

ALOE, or ALOES, in pharmacy, the inspissated juice of the aloe perfoliata, asiatic aloe, prepared in the following manner: from the leaves, fresh pulled, is pressed a juice, the thinner and purer part of which is poured off, and set in the sun to evaporate to a hard yellowish substance, which is called succotrine aloe, as being chiefly made at Succotra. The thicker part, being put into another vessel, hardens into a substance of a liver-colour, and thence called aloe hepatica. The thickest part, or sediment, hardens into a coarse substance, called aloe sabaling, or the horse-aloe, as being chiefly used as a purge for horses.

Fabroni has discovered that the recent

juice of the leaves of the aloe has the property of absorbing oxygen, of assuming a fine reddish purple, and of yielding a pigment which he strongly recommends to the artist.

ALOPECURUS, fox-tail-grass, in botany, a genus of the Triandria Digynia class of plants, and of the natural order of Grasses, the calyx of which is a bivalye glume, containing a single flower: the valves are hollow, of an ovate lanceolated figure, equal in size, and compressed; the corolla is univalve; the valve is concave, and of the length of the cup, and has a very long arista inserted into its back near the base. There is no pericarpium: the corolla itself remains, and contains the seed, which is single and of a roundish figure. There are 12 species. The A. pratensis, meadow foxtail, is a native of most parts of Europe, and is found with us very common in pastures and meadows. It is perennial, and flowers in May. This is the best grass to be sown in low meadow grounds, or in boggy places which have been drained. It is grateful to cattle, and possesses the three great requisities of quantity, quality, and earliness, in a degree superior to any other, and is therefore highly deserving of cultivation in lands that are proper for it. The seed may be easily collected, as it does not quit the chaff, and the spikes are very prolific; but the larvæ of a species of muscæ, which are themselves the prey of the cimex campestris, devour the seeds so much, that in many spikes scarcely one is found perfect. A. agrestis is a very troublesome weed in cultivated ground, and among wheat it is execrated by farmers, under the name of blackbent; it is also common by way-sides, as well as in corn-fields, and in pastures in the Isle of Wight. It has acquired the name of mouse-tail grass in English, from the great length and slenderness of the spike, which resembles the tail of a mouse. It is annual, and flowers in July, continues flowering till autumn, and comes into bloom very soon after being sown.

ALPHABET, in matters of literature, the natural or accustomed series of the several letters of a language.

As alphabets were not contrived with design, or according to the just rules of analogy and reason, but have been successively framed, and altered, as occasion required, it is not surprizing that many grievous complaints have been heard of their deficiencies, and divers attempts made to establish new and more adequate ones in their place.

All the alphabets extant are charged by Bishop Wilkins with great irregularities, with respect both to order, number, power, figure, &c.

As to the order, it appears (says he) inartificial, precarious, and confused, as the vowels and consonants are not reduced into classes, with such order of precedence and subsequence as their natures will bear. Of this imperfection the Greek alphabet, which is one of the least defective, is far from being free for instance, the Greeks should have separated the consonants from the vowels; after the vowels they should have placed the dipthongs, and then the consonants; whereas in fact, the order is so perverted that we find the goy the fifteenth letter, in order of the alphabet, and the ɗa, or long o, the twenty-fourth and last, the the fifth, and the the seventh.

With respect to number, they are both redundant and deficient; redundant, by allotting the same sound to several letters, as in the latin c and k, ƒ and ph; or by reckoning double letters among the simple elements of speech, as in the Greek and 4, the Latin qor cu, x or ex, and the j consonant; deficient in many respects, particularly with regard to vowels, of which seven or eight kinds are commonly used, though the Latin alphabet takes notice only of five. Add to this, that the difference among them, with regard to long and short, is not sufficiently provided against.

The powers, again, are not more exempt from confusion; the vowels, for instance, are generally acknowledged to have each of them several different sounds; and among the consonants we need only bring as evidence of their different pronunciation, the letter c in the word circa, and g in the word negligence. Hence it happens, that some words are differently written, though pronounced in the same manner, as cessio and sessio; and others are different in pronunciation, which are the same in writing, as give, dare, and give, vinculum.

Finally, the figures are but ill-concerted, there being nothing in the characters of the vowels answerable to the different manner of pronunciation; nor in the consonants analogous to their agreements or disagreements.

Alphabets of different nations vary in the number of their constituent letters. The English alphabet contains twenty-four letters, to which if j and v consonants are added, the sum will be twenty-six; the French, twenty-three; the Hebrew, Chaldee, Syriac, and Samaritan, twenty-two each; the Ara

bic, twenty-eight; the Persian, thirty-one; the Turkish, thirty-three; the Georgian, thirty-six; the Coptic, thirty-two; the Muscovite, forty-three; the Greek, twenty-four; the Latin, twenty-two; the Sclavonic, twenty-seven; the Dutch, twenty-six; the Spanish, twenty-seven; the Italian, twenty; the Ethiopic, as well as Tartarian, two hundred and two; the Indians of Bengal, twenty-one; the Baramos, nineteen; the Chinese, properly speaking, have no alpabet, except we call their whole language their alphabet: their letters are words, or rather hieroglyphics, and amount to about 80,000. If alphabets had been constructed by able persons, after a full examination of the subject, they would not have been filled with such contradictions between the manner of writing and reading, as we have shewn above, nor with those imperfections that evidently appear in the alphabets of every nation. Mr. Lodowick, however, and Bishop Wilkins, have endeavoured to obviate all these, in their universal alphabets or characters. See CHARACTER.

It is no wonder that the number of letters in most languages should be so small, and that of words so great, since it appears that allowing only 24 letters to an alphabet, the different words or combinations that may be made out of them, taking them first one by one, then two by two, &c. &c. would amount to the following number:-1391, 724288, 887252, 999425, 128493, 4022000. See COMBINATION. It must be admitted nevertheless, that the condition that every syllable must contain at least one vowel, would modify this number in the way of denomination; but on the other hand the combinations in polysyllabic words would operate the contrary way.

Many learned authors have composed inquiries into the origin of alphabetic writing, and not a few have referred the invention to the immediate inspiration of God. Nevertheless it appears to be a very simple and direct improvement of the heiroglyphic art. Sensible objects are depicted in outlines by children, and most rude nations; and, as in the construction of languages, so in this writing by figures, substantives will come to be used adjectively, to denote relations or qualities. As words become more complex and less perfect by the use of abstractions, so likewise must the hieroglyphic pictures become combined and imperfect, and at length must have denoted things very different from any object capable of being delineated: and among other conse