to Prop. 15, are undoubtedly the demonftrations which Sir Ifaac Newton himself would have given.

The theorem marked (r) pag. 109, is curious, and the demonftration such as might be expected from fo masterly a hand. Nor must we omit to mention the method of finding two mean proportionals, pag. 152, as it is performed with equal elegance and perfpicuity.

In a word, the whole of this commentary is remarkably clear and inftructive; but the illuftrations of fome parts of the 9th section, book 1. of the Principia, deserve to be distinguished.

We could however wish that the ingenious gentleman concerned in this work had confidered more minutely the lunar inequalities; and we hope that, in the next edition, he will treat that fubject in a more copious manner.

But a ftill more acceptable prefent to the republic of letters would, we imagine, be, a commentary on the whole Principia, executed by the fame masterly hand; being perfuaded, that the difficulties which now attend the reading of that celebrated work wou'd then, in a great measure, be removed, and the British youth enabled to perufe the writings of their illuftrious countryman with ease and fatisfaction, without having recourfe to the labours of any foreigner.

B.

Models of Converfation for Perfons of Polite Education. Selected and tranflated from the French of M. l'Abbé de Bellegarde. 8vo. 5s. Millar.

HE French are doubtlefs the most artificial and systematic people in Europe. They have a whole ftring of arts and fciences unknown to other nations. Their Arts de Vivre, indeed, are not all of them admitted into the Encyclopedie; but there is no doubt we fhall fee many of them in a future edition, or a fupplement. Their refinements in the art culinary, in particular, have elevated la bonne chere into a science; while the mere knack of frying pancakes may not be improperly called a profound and fagacious improvement in meta-fritters. As they are not a whit lefs remarkable alfo for talking than eating, it is no wonder they fhould attempt, in like manner, to investigate the theory of converfation, and affect a fyftem in the art of discourse. It must be allowed that thefe lively people appear to be perfectly well qualified for an investigation of the fift principles of colloquial loquacity; but we conceive it will be found, on impartial examination, that, although the French talk much in company, they converfe less than some other nations, ftigmatized for their taci

turnity

turnity. Converfation is the reciprocal communication of our fentiments, for the improvement or entertainment of each other; and this can be no better fupported where all are talking together, than where all are equally filent. The French nation, therefore, appears to be little qualified for furnishing the best rules or models of converfation. Add to all this, that, as there. are talents which cannot be communicated, so there are modes of exerting them which cannot poffibly be taught. Of this kind, we apprehend, is the gift or talent of converfing. We are certain, at leaft, if it be an art, it is to be acquired only by imitation and practice, and never fcientifically. The man who hath learned to talk, like a parrot, only by rote, is undoubtedly a coxcomb in his difcourfe; but he may frequently prove a more agreeable, and even instructive, companion, than the pedant who hath learned to talk only by book.

Admitting, however, that a work of this nature might be of fome ufe to fome fort of readers, it is certainly not thofe, for whom' the models before us are profeffedly written, viz. perfons politely' educated: every qualification that is to be acquired in this way, being effected only by a polite education. If this does not qualify us for converfation, we are apprehenfive no literary models will have fo defirable an effect. But, were the defign in general unexceptionable, we should bestow but little applaufe on these fpecimens of the Abbé de Bellegarde's performance; notwithstanding the approbation it may have met with from many of his countrymen. We fhall do him the juftice, however, to let him fpeak a few words in his own recommendation.

'Converfation, fays he, if put to its right ufe, contributes greatly to fweeten fociety, and render life more agreeable. There is not perhaps a more exquifite pleasure, a fatisfaction more delightful, than what arifes from the acquaintance of men of fense: But the misfortune is, the world abounds with trifling people, tiresome, infipid, impertinent, and yet full of themselves; who, troublesome as they are, affect to put on the man of confequence, and to be thought the foul of company. Such as these make folitude regreted what they fay is low, trivial, and puerile; barren of any charm for one's attention, vulgar, and uncouth. They are ever talking too, and yet one can diftinguish little but found. Is it then any wonder that converfation generally tires?

• What is ftill more incomprehenfible, is, that certain people, who do not want fenfe, knowlege of the world, nor yet good breeding, tire you as much as others, and their vifits are as wearifome if they happen to be too long. And either this is because they will not be at the trouble of keeping up a converfation, or elfe have not the address to enter into the taste and genius of the perfons they converfe with.

P4

< The

The great art of pleafing in converfation is to proportion it to the level of the company you are in, and to raise or lower one's style according to the measure of their understandings, and the occafions of the fubject you are upon. There is no reason to get by heart what to fay'; for common converfation admits of nothing ftudied or affected: chance, the times, and the difpofition of the company, fhould alone give it birth. And accordingly, in thefe models of converfation, we have not fet people a talking for two hours together upon the fame fubject, till they are quite out of breath: this would have been tirefome. But what we would infinuate herein, is, that morality, hiftory, politics, and the various events of life, are inexhauftible sources of polite converfation, for perfons who have any taste for the belles lettres.

Though the pieces of history herein related are fufficiently detached from each other, yet care has been taken in fuch manner to adjuft and link them together, that they feem fo to fuccecd one another as to form a connected and coherent discourse; infomuch, that one paffes infenfibly from one reflection to another, without ever perceiving the difference of the subject. And this variety is perhaps not unacceptable. It will not be unpleafing to men of letters, to find in thefe converfations, as it were, an affemblage that will put them in mind of what they have read. And others will here difcover what they did not know before; and may hence too learn how to distinguish what is worth remarking in books, and how to convert paflages of history and morality to their own benefit, by rendering them fubfervient to the civilizing their minds, and the regulation of their own behaviour and moral conduct in life

Thus far our polifhed Abbé: It is after all, however, very certain, that thefe difcourfes might contribute to all the purpofcs the Author here fpecifies, without anfwering the profeffed end and intention of them as models of converfation. In this light we conceive them to be extremely defective; being nothing more than a dull repetition of hiftorical anecdotes, now and then intermixed with a few trite and common-place reflections in which all parties fo far agree, as to give rife to no fpirit of altercation; without which, all difcourfe, however refined, learned, or fentimental, is tedious and infipid. Arfennes, Ariftus and Timanthes, fucceflively recite all the feveral paffages they can recollect, from the Greck, Roman and French histories, relative to the topic of converfation; and then their difcourfe ends. At the lame time, none of the interlocutors are invefted with any diftinguishing character; the one talking much in the fame ftrain as the other; and juft in the fame fentiments, except where it is neceffary to introduce two different hiftorical accounts of the fame fact or perfonage. There are perhaps no

models

models of conversation superior to the colloquies of Erafinus. Not indeed that they are fo polite as those of our Author; but then they are much lefs dull in proportion.

We shall not take the trouble to controvert any of this Author's fentiments, or to criticise on the various facts by which they are fupported; let it fuffice to fay, that the former are frequently as abfurd, as the latter are improbable. This work had, indeed, but one thing to recommend it, even in the original, and that was its ftyle. Unhappily the Tranflator has deprived it of even that merit, in his English verfion, which is most execrable*.

*We conceive the Tranflator must be a foreigner, as we think no native would make ufe of the genitive cafe and the pronoun poffeffive at the fame time, as this Writer frequently does. Thus he fays, Auguftus's grandfon, whofe murder was but a prelude to that of Germanicus's. And again, fhe fupported the Duke of Orleans's interefts against thofe of his brother's,'-What Englishman alfo could be fo ignorant of the meaning of words, as to fay, A good fhepherd will fheer the wool, but not fleece his sheep.'. What is fleecing, if it be not sheering off the wool ? Fleecing is not flaying, Mr. Tranfla or! If you are a Frenchman you are the more exc fable in this particular; but a man should understand two languages before he ventures to tranflate,

K-n-k.

Supplement to the Treatife on Ship-building, containing Extracts tranflated from M. Bouguer's Traité du Navire. Together with 'M. Duhamel's Method of finding the Center of Gravity. With fome occafional Remarks. Alfo an Account of feveral Experiments, made to afcertain the Form of a Solid which will move with the greatest Velocity through the Water. Likewife a Method to determine the Thickness of the Plank, in the Direction of the Planes of the Timbers. With the Proportions for Mafis, Yards, Caps, &c. By Mungo Murray. 4to. 5s. Millar.

N the introduction to the work before us, Mr. Murray, after

perties of every fhip, very juftly concludes, that it will be abfolutely neceffary for all fhips to be longer than they are broad, and not only tapered at each end, but alfo from the extreme breadth down to the keel. The next enquiry, he obferves, 'muft be, whether these vertical fections are to be limited with curves or ftrait lines, and how to afcertain their form.

The mathematicians, adds Mr. Murray, have endeavoured to investigate the form of that folid, which meets with least refiftance in paffing through the water; but they have not drawn

any practical rules from thence, to determine the form of a fhip; and fhould they be fo lucky, after a tedious calculation, as to find out the particular form of fuch a folid, it would be of little ufe in forming the body of a fhip: for it is fuppofed that the folid is to continue in the fame pofition in the water, otherwife the immerged part will alter its form as often as it alters its pofition, unless it be, as M. Bouguer would have it, formed by the -Revolution of a curve round its axis. Hence we may conclude, that the particular form of a fhip cannot be determined by rules" that will admit of a mathematical demonftration.'

Is it poffible that a perfon who has undertaken to abridge fo curious a treatife as that of M. Bouguer's Traité du Navire, can be ignorant that the folid of leaft refiftance is formed by the revolution of a curve round its axis! But if he does not know this, he would do well to perufe the Scholium to the 34th Prop. Book II. of Sir Ifaac Newton's Principia; and the demonftration of that Scholium, inferted at the end of Motte's tranflation.

The builders, continues our Author, finding they could have very little affiftance from the mathematicians, have applied themfelves to experience; and though they have not found any particular form which may be a ftandard for all fhips of the fame burthen, and defigned for the fame fervice, yet in fome points they feem to agree. Hence it is, that, in fhips of war of the fame rate, the principal dimenfions are nearly the fame; and in all ships the midship frame is nearer the fore-part than the afterpart. For finding, by repeated trials, that a maft, or tree, when tapered, will tow fafter through the water with the butt end foremost, than with the fmall end, they conclude it will be so in fhips; though Mr. Bouguer thinks the only reafon for towing the but-end foremoft is, that the rope may not flip.'

If Mr. Murray means a maft, whofe heel or but-end is cut tapering, in order to fit the step in the keelson, the refult of the experiments he mentions may poffibly be just: but if he means a maft nearly in the form of a fruftum of a cone, whose bases are at right angles to the axis, he must be mistaken, in all probability, from the experiments not having been made with a fufficient degree of accuracy.

C

B

For let BC FG reprefent a maft or tree in the form of a fruftum of a cone. It is well known that the refiftance of the water, or the whole efficacy of the G force of all the ftrokes of the particles of the.

fluid against the end FG of the fruftum, is to the refiftance

against