In 1730, Dr. John Clarke published A Demonstration of some of the principal sections of Sir I. Newton's Principles,' &c. This work contains the greater part of the first book somewhat expanded, and with the applications of the third book intermixed. But it omits the most important part of the eleventh section: nevertheless, a student who should join with Dr. Clarke's work the article GRAVITATION in the present one, would have the most important parts of the Principia, as far as is necessary to gain an insight into New

ton's methods.

In the same year, 1730, George Peter Domck published his Philos. Math. Newt. Illustrata Tomi Duo, Londini.' (This work is inadvertently called an edition of the Principia in NEWTON, and its author's name is spelled Donick.) The first volume of it is only a preparatory course of mathematics; the second gives a large part of the first book in Newton's manner, and gives more of the results of the eleventh section. It also enters upon some of the numerical applications of the third book.

The Commentary of the Minims (Jesuits they are usually but wrongly called) Le Sueur and Jacquier (1739) is an excellent performance for its time, considered as attempting to smooth the details of the mathematical difficulties. It uses algebra freely, but is totally insufficient to show the use of the differential calculus as now known; but it very frequently develops satisfactorily a point at which Newton only hinted.

Emerson's' Short Comment on Newton's Principia,' 1770, is a brief explanation of some of the mathematical difficulties and obscurities, followed by defences of the Principia, the Optics, and the Chronology. Emerson defended everything of Newton's.

The popular explanations of Maclaurin, Pemberton, and Voltaire are too widely known to need description; they do not much help the mathematical student. Many so-called explanations of Newtonian philosophy (such as Benjamin Martin's, 1751) are literally nothing but treatises on general physics.

The most celebrated comments in the way of objection are those of Leibnitz, John Bernoulli, and Huyghens [HryGHENS]; the first and second real admirers of the genius of Newton, the third also an admirer after his fashion. Many of their remarks may be found in the published correspondence of the first two, but the history of the effect produced by the Principia in the years following its publication is scattered in too many places for us to attempt to give the particular publications which should be consulted. PRINCIPLE, D'ALEMBERT'S. [FORCES, IMPRESSED AND EFFECTIVE; VIRTUAL VELOCITIES.]

PRINGLE, JOHN, the youngest son of Sir John Pringle, Bart., and Magdalen Eliott, the sister of Sir Gilbert Eliott, Bart., was born at Stichell-House in Roxburghshire, April 10, 1707. Having received at home, under a private tutor, the elements of a classical education, he entered the university of St. Andrews, where a relative of his father, Mr. Francis Pringle, was at that time professor of Greek. After keeping the ordinary number of terms, he removed to Edinburgh, in October, 1727, in order to qualify himself for the medical profession; but in the year following he proceeded to the university of Leyden. It is stated by Dr. Kippis, on the authority of Mr. James Boswell, that Pringle was at one time intended to follow a mercantile life, and that on leaving Edinburgh he went to Amsterdam for that purpose, but that his attention was accidentally drawn to the study of medicine by attending a lecture of Boerhaave in the university of Leyden. He entered this university in 1728, and took the degree of doctor of physic, 20th July, 1730, his diploma bearing the signatures of Boerhaave, Albinus, Gravesande, and other eminent individuals. His inaugural dissertation was entitled De Marcore Senili.' On quitting Leyden, he proceeded to Paris, where he completed his medical studies, after which he settled as a physician at Edinburgh. He had not however given his attention exclusively to medicine. In 1734 he was appointed by the magistrates and council of Edinburgh to the professorship of moral philosophy in the university of Edinburgh, jointly with Mr. Scott, during the life of the latter, and solely after his decease. Dr. Kippis says he was appointed to the chair of pneumatics and moral philosophy, but no mention of the former of these sciences is to be found in any other notice of Pringle's life to which we have referred. He continued to practise at Edinburgh as a physician till 1742, when he was nominated physician to the Earl of Stair, who then commanded the allied armies of England and Austria, and through whose recommendation he received the same year the further appointment of physician to the military

Mr. Airy's development and extension of the results of the cleventh section (which forms the article GRAVITATION in this work) places one of the methods of the Principia, and one which ought to last, within the reach of every student. It is unique, the difficulties of the eleventh section having left it almost without a commentator, and altogether without an explainer; and it takes in several of the discoveries of the present time.

Many commentaries on the Principia have been written at Cambridge by private tutors for the use of their pupils, of which some have been printed. Of the following we have never seen more than the title: Excerpta quaedam e Princ. Phil. Nat., cum notis variorum,' Cambridge, 1765. There is Carr's three sections of Newton, a modern work, and an exposition of various parts of the Principia, contained in the second edition of Professor Whewell's Dynamics.'

To give a view of the foreign objections to Newton's system, at the time of its first introduction, the following works may serve: 1,Collection of Papers which passed between Mr. Leibnitz and Dr. Clarke, in 1715 and 1716,' by Dr. Samuel Clarke; London, 1717. 2, Traité de Paix entre Des Cartes et Newton,' by the Jesuit Aimé-Henri-Paulian; Avignon, 1763. 3, 'Le vrai Systême de Physique générale

for life. He was present at the battle of Dettingen (26th June, 1743), shortly after which he was promoted by the Duke of Cumberland, second son of George II., to be physician-general to his majesty's forces in the Low Countries, whereupon he resigned his professorship. The benevolence of his disposition and the exemplary zeal and ability with which he discharged his official duties while connected with the army, are attested by all who knew him. Impressed with the suffering frequently attendant on the sudden movement of an army, which necessitated as sudden a removal of the hospitals or the abandonment of the men to the doubtful generosity of an enemy, he applied himself earnestly to the consideration of the means whereby it might be mitigated or removed. Prior to this it had been the custom to place the sick and wounded at a distance from the army, but even then it often happened that a posttion of salubrity was incompatible with one of safety. Through his exertions a convention was entered into, in the early part of the campaign of 1743, between Lord Stair and Marshal Noailles, for the mutual protection of the hospitals of both armies. This convention was faithfully adhered to by both the French and English generals. Pringle's situation afforded ample opportunity of observing the influence of climate, diet, confined and humid quarters, habits of intemperance and uncleanness, &c. These, with

Locality, Habits, &c.-Abundant in many parts of Java, near villages and gardens, in the confines of which, among trees and shrubs, it builds its nest. It is a sprightly bird, sporting among the branches in short and rapid flights, and has received its native name from its lively and pleasant notes. (Horsf.

Mr. Swainson (Classification of Birds) thinks that Prinia may be a subordinate type or subgenus of Drymvica. [SYLVIADE] He observes that the Prinice have all the activity and familiarity of the true Wrens (Troglodytes), and so much resemble them in general appearance, in their short sweet song, and the throwing up of the tail, that it is not very surprising that they should have been classed with the scansorial creepers.

In the article PLOVERS, Himantopus Melanogaster is erroneously printed under the cut instead of Himantopus Melanopterus, as well as in four places in the adjoining columus. The reader is requested to substitute melanopterus' for melanogaster,' in each of these cases.

PRINSEP, JAMES, was descended from a family of Swiss extraction which had been some time settled in England. He was born in the year 1800, and went out to the East Indies at an early age in the service of the East India Company in the Mint department. On his arrival in India he was appointed assay master at Benares, where he remained about ten years. Here he collected the materials of his Sketches of Benares,' which perhaps give some of the best representations of Indian life yet published. He planned and constructed many works of public utility, and engaged in a valuable series of statistical inquiries connected with Benares. At this time he wrote an elaborate memoir on the mode of determining accurately the point at which the precious metals fuse, which was published in the 'Philosophical Transactions. Subsequently he was elected a Fellow of the Royal Society.

When the Benares mint was abolished, Prinsep was transferred to that at Calcutta. He had previously contributed to the Gleanings of Science,' conducted by Capt. Herbert, and on the departure of that gentleman from Calcutta he became the secretary to the physical class of the Asiatic Society, and editor of the 'Gleanings,' which he remodelled in 1832, under the title of the Journal of the Asiatic Society,' a work which has contributed in an eminent degree to the extension of every species of information in India. His attention having been directed to the subject of Bactrian coins, he made numerous discoveries which enabled him to fill up the blank left in the history of the successors of Alexander the Great in Bactria, and constructed a nearly unbroken series of numismatic records, which extended from the Macedonian king to modern times.

On the departure of H. H. Wilson for England in 1832, he became secretary to the Asiatic Society, and he now began to follow up the steps of Jones, Colebrooke, and Wilson, in the field of Indian antiquities. Meantime his labours as editor of the Journal' were unabated; he was in a great measure the engraver and lithographer for it; and he carried on an extensive correspondence in India and with Europe, besides contributing a number of valuable articles on a great variety of subjects, especially chemistry. mineralogy, Indian numismatics, and Indian antiquities. The most interesting of his discoveries is the deciphering of inscriptions which had remained a sealed book to all previous Orientalists, and which are important as connecting the history of India with that of Europe: the name of Antiochus the Great and the mention of his generals as commanding in the north of India, occur in two edicts of Asoka, or Piyadasi, king of India.

Under the weight of these and other labours his health began to break down. It was hoped that a voyage to England would restore him; but after an illness of eighteen months, he died, on the 22nd of April, 1840, in the 40th year of his age. His case is said to have borne a considerable resemblance to that of Sir Walter Scott. His death has left a blank in the progress of knowledge and civilization in India which will not perhaps be readily filled up.

(Delhi Gazette, July 8, 1840; Proc. Roy. As. Soc., 1840.) PRINSE PIA, a genus of plants of the natural family of Chrysobalaneæ, so named by Dr. Royle in honour of James Prinsep, the late distinguished secretary of the Asiatic Society of Calcutta, in consequence of his contributing, by his researches into the meteorology of India, to the progress and right understanding of the geography of plants, an important branch of botany. The genus consists of only a single species, remarkable for its thorny appearance, but it may be considered typical of the labours of the individual whom it is designed to commemorate, as, early in the season, it is conspicuous for the abundance of its inflorescence, and, later, for that of the purple-coloured berries with which it is loaded. The seeds are large, and yield by expression an oil which is highly esteemed by the mountaineers of the Himalayas, where it is indigenous, and which by Europeans is thought a good substitute for salad oil.

PRINTING, in the widest sense of the word, may be defined to be the art of producing copies of any writing or other marks by pressure, either upon a substance so soft as (like wax or clay) to take the shape, whether in relief or by indentation, of the stamp applied to it, and yet not so perfectly fluid (like water) as to refuse to retain the form so given to it, or upon a substance sufficiently bibulous or otherwise attractive as to receive colour from some pigment with which the stamp is daubed. The essence of printing is the production of a copy by pressure. Correctly speaking however it is not an exact copy or fac-simile which printing produces in any case; so far from that, wherever the surface is raised in the stamp, it is sunk in the impression, and vice versa, and even a merely coloured mark is always reversed in form; but, what is alone of importance, all the impressions are exact copies of one another, and also bear a certain and perfectly assignable relation to the stamp or type.

Even on a theoretical view of the subject, printing by means of merely a variegated surface of stamp, or, in other words, the reproduction, in soft substances, of cameos and intaglios, would seem to be the simpler and more obvious of the two kinds of printing we have mentioned. This may be said to be printing by pressure alone. In the other kind of printing, by the transference of colour, there is required the introduction, in addition to the type and its recipient, of a third element or agent, namely, the colour to be transferred. And this was an addition very little likely ever to be made until the idea of multiplying copies of coloured marks had itself occurred, that is, until the very object had been thought of which this was the only means of accomplishing, and which was the only object this process was suited to accomplish. Having a seal or cut stamp in his hand, the making an impression with that upon wax or any other soft substance was extremely natural for a person wishing on any occasion to leave his mark or sign; it was the same thing, in fact, with notching a piece of wood or stone with a knife or other sharp instrument, with this difference only-that the knife makes its marks by excision, or altogether removing and abstracting part of the substance operated upon; the stamp, by extrusion, or merely pushing it aside. Or still more nearly it resembles the rudest and

with the picture, although in other cases they seem to have been subsequently inserted from moveable types. The probability is that at first the Speculum' was entirely a block book, but that in subsequent editions the block-printing was mixed with printing from moveable types: the few copies that have come down to modern times are perhaps made up of leaves collected from several impressions, some in which moveable types were and others in which they were not used. Like the Biblia Pauperum,' it has no date; but it is generally admitted to have in all probability been first printed before 1440. Another block-book that was frequently printed, and which is noticeable as consisting wholly of text, without pictures, was the small Latin Grammar of Donatus, the common school-book of those days. These block-books are, like the Chinese books at this day, printed only on one side of the leaf; and they appear to have all been produced in the Low Countries.

At this point, as we have already observed, printing would have stopped, if the art of alphabetic writing had remained undiscovered. At most, the art could not have been carried beyond what has been called logography, or the printing with types each containing a whole word, a method which is in partial use in China, and has even in recent times been attempted among ourselves, but which is manifestly of very limited application. Logography, indeed, is merely a modification of block-printing; the principle is the same whether the block or type contain a whole word, a whole line, a whole sentence, or a whole page. It is not unlikely however that the partial employment of logography in the infancy of European printing may have been what suggested alphabetic printing. There is good evidence that some words of common occurrence were early cut out on separate stamps or types; and although this may have been done only after the invention of alphabetic printing, to save the trouble of composition (or setting up the words from the letters), it is possible that the same thing may also have been done while only block-printing was known, with the view of saving the repeated cutting out of the same words. If so, the perception, thus awakened and turned to account, of the fact that two different pages often contained some words in common, would be apt, it may be thought, to conduct to the reflection that all words and all pages that could be printed were composed out of the same twenty-four letters, and that therefore if a sufficient number of types consisting each of a single letter could be provided, the same types that had been made use of in printing any one page might, with the mere trouble of re-arrangement, be made to serve for printing any other. Here was what we may call quite a new principle. Logography was indeed the employment to a certain extent of moveable types; but the principle of moveable type printing was no more there than we can say the principle of alphabetic writing is to be found in the 214 radical characters of the Chinese. The universality which is the essence of a principle is equally wanting in both cases.

Yet, whether it may have been arrived at through the medium of logography or not, it may be safely affirmed that, where alphabetic writing was known, alphabetic printing could not be long in being found out. It was in fact in a manner already invented, in the co-existence of pigment printing on the one hand, and of alphabetic writing on the other; for it was the mere resultant, without the assistance of any third element, of the combination of these two ideas. Not that even this simple combination would of necessity be immediately made; the history of discovery sufficiently attests that it will often be a considerable time before a third thing is thought of which would be at once accomplished by the mere bringing together, and into simultaneous and accordant action, of two things already familiarly known and practised; but still, fortuitously or through reflection and experiment, the new idea is much more likely to be struck out in these circumstances than if a more complex combination were required to produce it, and, especially where the state of society supplies any considerable stimulus to the attainment of it, cannot be very long in being arrived at.

the production of such types by the process of casting them in metal, and the formation of the matrix, or mould, by means of the punch, or stamp of hardened steel by which the matrix is impressed or hollowed out; these, disregard ing mere mechanical facilitations, may be considered as the three great organic revolutions by which block-printing was transformed into the art as it now exists. They are far, indeed, from being upon a level in point of importance; they descend in value in the order in which we have enumerated them, which must also have been the order in which they followed each other; and the third contributes so little to the completion of the invention, as compared with either the first or second, that we might perhaps without much in justice omit it altogether. Yet, strictly considered, it too has the same characteristic with the others of converting a process of mere imitative copying into one of what we may call identical reproduction, or, in other words, substituting the unity of a single mechanical operation for a succession of separate manipulations. The invention of printing may be said to be, in all its parts, distinguished from mere writing by this very characteristic; this is throughout its principle, and that in which it consists; in block-printing, the page, having been once cut out upon the wood, is afterwards reproduced by a single touch of the inking-brush as perfectly as it could be by retracing every line of every letter with the pen; by the employment of moveable types, the same letters which have already served to print one book are made to print any other, without a new cutting, however new the matter, or any further trouble except a rearrangement of them; by the art of founding or casting the types in metal, the separate fabrication of every single type is done away with, and any number of types of the same character are obtained by merely dropping the metal into the matrix; and, finally, by the contrivance of the punch, matrices themselves are thus mechanically multiplied as well as types. Pigment stamping, the breaking up of the block-page into single letters, the substitution of letters of cast metal for those of cut wood, and the production of many matrices from one punch, the four successive steps constituting the invention of printing, have thus all one end and aim. This very circumstance might enable one of them in a great measure to suggest another.

Simple as the first of the four successive discoveriesstamping or printing with a pigment-may be thought, it was perhaps both the most important and the most difficult to achieve of the whole. Even if the art of printing had never been carried farther than the Chinese have carried it, how precious a gift of heaven would it not still have been! how incalculably would it not have elevated the function of written language! Indeed that primitive sort of printing would have been all-suflicient, and in every respect the best, in all those numerous instances in which stereotyping (essentially the same thing) is now resorted to, even in countries possessing an alphabet; and a time perhaps is coming when in all countries the increase in the number of readers may make that kind of printing the kind most employed, as it probably would be in China from that cause alone, even did the nature of the written language admit of the employment of moveable types. The idea of producing an impression by a coloured stamp would seem also to have lain very remote from ordinary operations and habits of thought; men had been using dry seals from the earliest times of Eastern civilization, but we find no trace of this other kind of stamping, at least for the purpose of multiplying writing, even in the East, till about nine centuries ago, and none in Europe till five hundred years later. Neither Egypt, nor Greece, nor Rome, had thought of this, with all their ingenuity, and among all their arts. He therefore, we may say, was truly a great genius who first meditatively conceived the notion of making an engraved seal or block thus produce a permanent impression of itself upon a hard sur face by merely besmearing it with a little colouring matter

simplest of all simple operations as that seems, now that we are familiar with it, and must have seemed indeed as soon as it had been even once performed.

alone the claims of the several individuals to whom the invention has been attributed have any reference, even the chief of them, the substitution of types containing each a single letter for blocks containing an entire page, must, we apprehena be considered as inferior to the primary