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penetrating smell, and very hot acrid

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SATURN is a very conspicuous planet, though not so brilliant as Jupiter. The period of his sidereal revolution round the earth is 10,759 days. He moves from west to east nearly in the plane of the ecliptic, and exhibits irregularities similar to those of Jupiter and Mars. He becomes retrograde both before and after his opposition, when at the distance of about 109° from the Sun. His retrograde motion continues about 139 days, and during its continuance he describes an arc of about 6°. His diameter is a maximum at his opposition, and his mean apparent diameter is 18". Saturn, when viewed through a good telescope, makes a more remarkable appearance than any of the other planets. Galileo first discovered his uncommon shape, which he thought to be like two small globes, one on each side of a large one, and he published his discovery in a Latin sentence, the meaning of which was, that he had seen him appear with three bodies, though, in order to keep the discovery a secret, the letters were transposed. Hav. ing viewed him for two years, he was sur prised to see him become quite round, without these appendages, and then, after some time to assume them as before. These adjoining globes were what are now called the anse of his ring, the true shape of which was first discovered by Huygens, about forty years after Galileo, first with a telescope of twelve feet, and then with one of twenty-three feet, which magnified objects one hundred times. From the discoveries made by him aud other astronomers, it appears that this planet is surrounded by a broad thin ring, the edge of which reflects little or none of the Sun's light to us, but the planes of the ring reflect the light in the same manner that the planet itself does, and if we suppose the diameter of Saturn to be divided into three equal parts, the diameter of the ring is about seven of these parts. The ring is detached from the body of Saturn in such a manner, that the distance between the innermost part of the ring and the body is equal to its breadth. Both the outward and inward rim of the ring is projected into an ellipsis, more or less oblong, according to the different degrees of obliquity with which it is viewed. Sometimes our eye is in the plane of the ring, and then it becomes invisible, either because the outward edge is not fitted to reflect the Sun's light, or more probably because it is too thin to be seen at such a

distance. As the plane of this ring keeps always parallel to itself, that is, its situation in one part of the orbit is always parallel to that in any other part, it disappears twice in every revolution of the planet, that is, about once in fifteen years, and he sometimes appears quite round for nine months together. At other times, the distance between the body of the planet and the ring is very perceptible, insomuch that Mr. Whiston tells us of Dr. Clarke's father having seen a star through the opening, and supposed him to have been the only person who ever saw a sight so rare, as the opening, though certainly very large, appears very small to us.

When Saturn appears round, if our eye be in the plane of the ring, it will appear as a dark line across the middle of the planet's disc, and if our eye be elevated above the plane of the ring, a shadowy belt will be visible, caused by the shadow of the ring as well as by the interposition of part of it between the eye and the planet. The shadow of the ring is broadest when the Sun is most elevated, but its obscure parts appear broadest when our eye is most elevated above the plane of it. When it appears double, the ring next the body of the planet appears brightest. When the ring appears of an elliptical form, the parts about the ends of the largest axis are called the ansæ, as has been already men. tioned. These, a little before and after the disappearing of the ring, are of unequal magnitude; the largest ansa is longer visible before the planet's round phase, and appears again sooner than the other. On the first of October, 1714, the largest ansa was on the east side, and on the twelfth on the west side of the disc of the planet, which makes it probable that the ring has a rotation round an axis. Herschel has demonstrated, that it revolves in its own plane in 10h 32′ 15.4". The observations of this philosopher have added greatly to our knowledge of Saturn's ring. According to him there is one single, dark, considerably broad line, belt, or zone, which he has constantly found on the north side of the ring. As this dark belt is subject to no change whatever, it is probably owing to some permanent construction of the surface of the ring: this construction cannot be owing to the shadow of a chain of mountains, since it is visible all round on the ring; for there could be no shade at the ends of the ring; a similar argument will apply against the opinion of very extended caverns. It is pretty evident that this dark zone is con.

tained between two concentric circles, for all the phenomena correspond with the projection of such a zone. The nature of the ring Dr. Herschel thinks no less solid than that of Saturn itself, and it is observed to cast a strong shadow upon the planet. The light of the ring is also generally brighter than that of the planet, for the ring appears sufficiently bright when the telescope affords scarcely light enough for Saturn. The Doctor concludes that the edge of the ring is not flat, but spherical, or spheroidical. The dimensions of the ring, or of the two rings with the space between them, Dr. Herschel gives as below:

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Breadth of the inner ring Breadth of the outer ring Breadth of the vacant space,

:

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or dark zone ............... 2,839 There have been various conjectures relative to the nature of this ring. Some persons have imagined that the diameter of the planet Saturn was once equal to the present diameter of the outer ring, and that it was hollow the present body being contained within the former surface, in like manner as a kernel is contained within its shell; they suppose that, in consequence of some concussion, or other cause, the outer shell all fell down to the inner body, and left only the ring at the greater distance from the centre, as we now perceive it. This conjecture is in some measure corroborated by the consideration that both the planet and its ring perform their rotations about the same common axis, and in very nearly the same time. But from the observations of Dr. Herschel, he thus concludes: "It does not appear to me that there is sufficient ground for admitting the ring of Saturn to be of a very changeable nature, and I guess that its phenomena will hereafter be so fully explained, as to reconcile all observations. In the meanwhile we must withhold a final judgment of its construction, till we can have more observations. Its division, however, into two very unequal parts, can admit of no doubt.” The diameters of Saturn are not equal: that which is perpendicular to the plane of his ring appears less by one-eleventh than the diameter situated in that plane. If we compare this form with that of Jupiter, we have reason to conclude that Saturn turns ra

pidly round his shorter axis, and that the ring moves in the plane of his equator. Herschel has confirmed this opinion by actual observation. He has ascertained the duration of a revolution of Saturn round his axis to amount to 0.428 day. Huygens observed five belts upon this planet nearly parallel to the equator.

SATYRIUM, in botany, a genus of the Gynandria Diandria class and order. Natural order of Orchides, Essential character: nectary serotiform, or twin-inflated behind the flower. There are twenty-one species.

SAUCISSE, or SAUSAGE, in the military art, a long train of powder, sewed up in a roll of pitched cloth, about two inches in diameter, serving to set fire to mines. There are usually two saucisses extended from the chamber of the mine to the place where the engineer stands; that in case one should fail, the other may take effect.

SAUCISSON, in fortification, a mass of large branches of trees bound together; and differing only from a fascine, as this is composed of small branches of twigs. Saucissons are employed to cover the men, and to make epaulements.

SAVILLE (SIR HENRY), in biography, a very learned Englishman, the second son of Henry Saville, Esq. was born at Bradley, near Halifax, in Yorkshire, November the 30th, 1549. He was entered of Merton College, Oxford, in 1561, where he took the degrees in arts, and was chosen fellow, When he proceeded master of arts, in 1570, he read, for that degree, on the Almagest of Ptolemy, which procured him the reputation of a man eminently skilled in mathematics, and the Greek language; in the former of which he voluntarily read a pablic lecture in the University for some time.

In 1578, he travelled into France, and other countries; where, diligently improv ing himself in all useful learning, in languages, and the knowledge of the world, he became a most accomplished gentleman, At his return, he was made tutor in the Greek tongue to Queen Elizabeth, who had a great esteem and respect for him.

In 1535, he was made Warden of Merton College, which he governed six and thirty years with great honour, and improved it by all the means in his power. In 1596, he was chosen Provost of Eton College; which he filled with many learned men. James I. upon his accession to the crown of England, expressed a great regard for him, and would have preferred him

either in church or state; but Saville declined it, and only accepted the ceremony of knighthood from the King, at Windsor, in 1604. His only son, Henry, dying about that time, he henceforth devoted his fortune to the promoting of learning. Among other things, in 1619, he founded, in the University of Oxford, two lectures, or professorships, one in geometry, the other in astronomy; which he endowed with a salary of 160l, a year each, besides a legacy of 6001, to purchase more lands for the same use. He also furnished a library with mathematical books, near the mathematical school, for the use of his professors; and gave 100l. to the mathematical chest of his own appointing; adding afterwards a legacy of 401. a year to the same chest, to the University, and to his professors jointly. He likewise gave 120l. towards the new building of the schools, beside several rare manuscripts and printed books to the Bodleian Library; and a good quantity of Greek types to the printing press at Oxford,

After a life thus spent in the encouragement and promotion of science and literature in general, he died at Eton College, the 19th of February, 1622, in the seventy. third year of his age, and was buried in the chapel there. On this occasion the University of Oxford paid him the greatest honours, by having a public speech and verses made in his praise, which were published soon after in 4to. under the title of "Ulti. ma Linea Savillii."

As to the character of Saville, the highest encomiums are bestowed upon him by all the learned of his time; by Casaubon, Mer. cerus, Meibomius, Joseph Scaliger, and especially the learned Bishop Montague, who, in his "Diatribæ upon Selden's His. tory of Tythes," styles him," that magazine of learning, whose memory shall be honourable amongst not only the learned, but the righteous for ever."

Several noble instances of his munificence to the republic of letters have already been mentioned in the account of his publications many more, and even greater, will appear. These are,

1. Four Books of the Histories of Corne. lins Tacitus, and the Life of Agricola, with Notes upon them, in folio; dedicated to Queen Elizabeth, 1581.

2. A View of certain Military Matters, or Commentaries respecting Roman Warfare. 1598.

3. Rerum Anglicarum Scriptores post Bedam, &c. 1596. This is a collection of

the best writers of our English History, to which he added chronological tables at the end, from Julius Cæsar to William the Conqueror.

4 The Works of St. Chrysostom, in Greek, in eight volumes, folio, 1613. This is a very fine edition, and composed with great cost and labour. In the preface he says, "that having himself visited, about twelve years before, all the public and private libraries in Britain, and copied out thence whatever he thought useful to this design, he then sent some learned men into France, Germany, Italy, and the East, to transcribe such parts as he had not already, and to collate the others with the best manuscripts." At the same time he makes his acknowledgements to several eminent men for their assistance; as Thuanus, Velserus, Schottus, Casaubon, Ducæus, Grater, Hoeschelius, &c. In the eighth volume are inserted Sir Henry Saville's own notes, with those of other learned men. The whole charge of this edition, including the several sums paid to learned men, at home and abroad, employed in finding out, transcribing, and collating the best manuscripts, is said to have amounted to no less than 8,000l. Several editions of this work were afterwards published at Paris.

5. In 1618 he published a Latin work, written by Thomas Bradwardin, Archbi-, shop of Canterbury, against Pelagius, entitled De Causa Dei contra Pelagium, et de virtute Causarum; to which he prefixed the Life of Bradwardin.

6. In 1621 he published a Collection of his own Mathematical Lectures on Euclid's Elements; in 4to.

7. Oratio coram Elizabetha Regina Oxoniæ habita, anno 1592. Printed at Oxford in 1658. 4to.

8. He translated into Latin King James's Apology for the Oath of Allegiance. He also left several manuscripts behind him, written by order of King James; all which are in the Bodleian Library. He wrote notes likewise upon the margin of many books in his library, particularly Eusebius's Ecclesiastical History; which were afterwards used by Valesius, in his edition of that work in 1659. Four of his Letters to Camden are published by Smith, among Camden's Letters. 1691. 4to.

SAUNDERS, or SANDERS. See SAN

TALUM.

SAUNDERSON (Dr. NICHOLAS), in biography, an illustrious professor of mathe matics in the University of Cambridge, and

a fellow of the Royal Society, was born at Thurlston in Yorkshire in 1682. When he was but twelve months old, he lost not only his eye-sight, but his very eye-balls, by the small pox; so that he could retain no more ideas of vision than if he had been born blind. At an early age, however, being of very promising parts, he was sent to the free school at Penniston, and there laid the foundation of that knowlege of the Greek and Latin languages, which he afterwards improved so far, by his own application to the classic authors, as to hear the works of Euclid, Archimedes, and Diophantes read in their original Greek.

Having acquired a grammatical education, his father, who was in the excise, instructed him in the common rules of arithmetic. And here it was that his excellent mathematical genius first appeared; for he very soon became able, to work the common questions, to make very long calculations by the strength of his memory, and to form new rules to himself for the better resolving of such questions as are often proposed to learners as trials of skill.

At the age of eighteen, our author was introduced to the acquaintance of Richard West, of Underbank, Esq., a lover of mathematics, who, observing Mr. Saunderson's uncommon capacity, took the pains to instruct him in the principles of algebra, and geometry, and gave him every encouragement in his power to the prosecution of these studies. Soon after this he became acquainted also with Dr. Nettleton, who took the same pains with him. And it was to these two gentlemen that Mr. Saunderson owed his first institution in the mathematical sciences; they furnished him with books, and often read and expounded them to him. But he soon surpassed his masters, and became fitter to teach, than to learn any thing from them.

His father, otherwise burthened with a numerous family, finding a difficulty in supporting him, his friends began to think of providing both for his education and maintenance, His own inclination led him strongly to Cambridge, and it was at length determined he should try his fortune there, not as a scholar, but as a master: or, if this design should not succeed, they promised themselves success in opening a school for him at London. Accordingly he went to Cambridge in 1707, being then twenty-five years of age, and his fame in a short time filled the University. Newton's Principia, Optics, and Universal Arithmetic, were the

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foundations of his lectures, and afforded him a noble field for the display of his genius; and great numbers came to hear a blind man give lectures on optics, discourse on the nature of light and colours, explain the theory of vision, the effect of glasses, the phenomenon of the rainbow, and other objects of sight.

As he instructed youth in the principles of the Newtonian philosophy, he soon became acquainted with its incomparable author, though he had several years before left the University; and frequently conversed with him on the most difficult parts of his works: he also held a friendly communication with the other eminent mathematicians of the age, as Halley, Cotes, De Moivre, &c.

Mr. Whiston was all this time in the mathematical professor's chair, and read lectures in the manner proposed by Mr. Saunderson on his settling at Cambridge; so that an attempt of this kind looked like an encroachment on the privilege of his office; but, as a good natured man, and an encourager of learning; he readily consented to the application of friends made in behalf of so uncommon a person.

Upon the removal of Mr. Whiston from his professorship, Mr. Saunderson's merit was thought so much superior to that of any other competitor, that an extraordinary step was taken in his favour, to qualify him with a degree, which the statute requires : in consequence he was chosen, in 1711, Mr. Whiston's successor in the Lucasian profes sorship of mathematics; Sir Isaac Newton interesting himself greatly in his favour. His first performance, after he was seated in the chair, was an inaugural speech made in very elegant Latin, and a style truly Ciceronian; for he was very well versed in the writings of Tully, who was his favourite in prose, as Virgil and Horace were in verse. From this time he applied himself closely to the reading of lectures, and gave up his whole time to his pupils. He continued to reside among the gentlemen of Christ College till the year 1723, when he took a house in Cambridge, and soon after married a daughter of Mr. Dickens, rector of Boxworth, in Cambridgeshire, by whom he had a son and a daughter.

In the year 1728, when King George visited the university, he expressed a desire of seeing so remarkable a person; and accordingly our professor attended the king in the senate, and by his favour was there created doctor of laws.

Dr. Saunderson was naturally of a strong healthy constitution; but being too seden. tary, and constantly confining himself to the house, he became a valetudinarian: and in the spring of the year 1739 he complained of a numbness in his limbs, which ended in a mortification in his foot, of which he died the 19th of April that year, in the 57th year of his age.

There was scarcely any part of the mathematics on which Dr. Saunderson had not composed something for the use of his pupils. But he discovered no intention of publishing any thing, till, by the persuasion of his friends, he prepared his Elements of Algebra for the press; which, after his death, were published by subscription in 2 vols. 4to. 1740.

He left many other writings, though none perhaps prepared for the press. Among these were some valuable comments on Newton's Principia, which not only explain the more difficult parts, but often improve upon the doctrines. These are published in Latin at the end of his postbumous Treatise on Fluxions, a valuable work, published in 8vo, 1756. His manuscript lectures too, on most parts of natural philosophy, might make a considerable volume, and prove an acceptable present to the public if printed.

Dr. Saunderson, as to his character, was a man of much wit and vivacity in conversation, and esteemed an excellent companion. He was endued with a great regard to truth; and was such an enemy to disguise, that he thought it his duty to speak his thoughts at all times with unrestrained free dom. Hence his sentiments on men and opinions, his friendship or disregard, were expressed without reserve; a sincerity which raised him many enemies.

A blind man, moving in the sphere of a mathematician, seems a phenomenon difficult to be accounted for, and has excited the admiration of every age in which it has appeared. Tully mentions it as a thing scarcely credible in his own master in philosophy, Diodotus; that he exercised himself in it with more assiduity after he be came blind; and, what he thought next to impossible to be done without sight, that he professed geometry, describing his diagrams so exactly to his scholars, that they could draw every line in its proper direction. St. Jerome relates a still more remarkable in stance in Didymus of Alexandria, who, though blind from his infancy, and there. føre ignorant of the very letters, not only

learned logic, but geometry also, to a very great perfection, which seems most of all to require sight. But, if we consider that the ideas of extended quantity, which are the chief objects of mathematics, may as well be acquired by the sense of feeling as that of sight, that a fixed and steady attention is the principal qualification for this study, and that the blind are, by necessity, more abstracted than others, (for which reason, it is said, that Democritus put out his eyes, that he might think more intensely), we shall perhaps find reason to suppose that there is no branch of science so much adapted to their circumstances.

At first, Dr. Saunderson acquired most of his ideas by the sense of feeling; and this, as is commonly the case with the blind, he enjoyed in great perfection. Yet he could not, as some are said to have done, distinguish colours by that sense; for, after having made repeated trials, he used to say, it was pretending to impossibilities. But he could with great nicety and exactness observe the smallest degree of roughness, or defect of polish, in a surface. Thus, in a set of Roman medals, he distinguished the ge. nuine from the false, though they had been counterfeited with such exactness as to deceive a connoisseur who had judged from the eye. By the sense of feeling also, he distinguished the least variation; and he has been seen in a garden, when observations have been making on the sun, to take notice of every cloud that interrupted the observation, almost as justly as they who could see it. He could also tell when any thing was held near his face, or when he passed by a tree at no great distance, merely by the different impulse of the air on his face.

His ear was also equally exact. He could readily distinguish the 5th part of a note. By the quickness of this sense he could judge of the size of a room, and of his distance from the wall. And if ever he walked over a pavement, in courts or piazzas which reflected a sound, and was afterwards con. ducted thither again, he could tell in what part of the walk he had stood merely by the note it sounded.

Dr. Saunderson had a peculiar method of performing arithmetical calculations, by an ingenious machine and method which has been called his Palpable Arithmetic, and is particularly described in a piece prefixed to the first volume of his Algebra. That he was able to make long and intricate cal. culations, both arithmetical and algebraical,

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