adapted to our own fervice makes its appearance: which, probably, may not foon happen. The work is divided into four parts. In the firft, M. Bourdé treats of the actions of fluids on the furfaces of folid bodies; the effects of these actions when the bodies which they act on are at liberty to obey the impulfe made on them; and of the centers of gravity and gyration of bodies: and having laid down the first principles of the motions of fluids, and of bodies after percuffion, in a plain and elementary manner, he proceeds to apply thofe principles in calculating the action of the wind on the fails of a fhip, and of the water on her rudder; and thence to determine the true and apparent velocities of the ship, with the direction of her motion. He demonftrates that the velocity of the thip will be as the fine of the angle of incidence of the wind on the fail, as long as the pofition of the fail, with refpect to the keel of the fhip, remains the fame; and he fhews that in order to remove from a coaft, or from any given line, at the greateft rate poffible, the tangent of the apparent angle of incidence of the wind on the fail must be double the tangent of the angle which the fail makes with the keel of the ship, at the fame time that the angle formed by the keel and the coaft is equal to the real angle of incidence. He next confiders the effect of those fails which are before, and those which are abaft, the center of gravity of the fhip, feparately, as well in regard to their force in urging the hip a-head, as in caufing her to fteer well; and, after fhewing from theory, the great ufe of the fprit-fail, jib, and fore ftay-fails, in caufing a fhip to fteer well, when failing by the wind, he juftly remarks, that we find by experience thefe fails yet more ufeful in this refpect than the theory makes them to be. The rudder becomes afterwards the object of our Author's confideration: he fhews, by reafonings, both obvious and natural, that it acts to the greatest advantage when it makes an angle of 45 degrees with the direction of the keel, and not when it makes an angle of about 55°, as hath been fo long infifted on in books of geometry; but, except in putting a fhip about, M. Bourdé juftly obferves, that the lefs neceffity there is for the action of the rudder the better. Under this article alfo, he very properly takes notice that, as fhips are generally conftructed, the rudder cannot act under a greater angle with the keel than about 30 degrees; and he propofes to augment the range of the rudder by fhortening the length of the tiller, and to compenfate for the power which which will be thus loft, by encreafing the diameter of the wheel we fteer by, or by dimin fhing the diameter of the barrel on which the tiller rope is wound. We are as well convinced, as M. Bourdé can be, of the benefit which would arife from encreafing the range of the rudder, and that it may be done by hortening the tiller: we are alfo perfuaded, that the power which which will be loft by fhortening the tiller may, in fome meafure, be replaced by reducing the barrel of the wheel, or by encreafing the diameter of the wheel itself; but we are at the fame time of opinion, that the encrease of power which can be gained by either or both of thefe means is very limited. For the barrel cannot be diminifhed much, without confiderably encreafing the number of turns which the rope will make on it; and which, befide the lofs of time it will occafion in shifting the rudder, will often caufe one turn to ride on another: and the diameter of the wheel cannot be greatly increafed, especially in line of battle fhips, because it is always placed under the poop, and therefore limited to the height of it. The fecond part of this work contains the application of the theory to practice, and exhibits reafons for all the evolutions that are to be performed with a fhip. The problems which are here refolved, relate to the manner of getting under fail when the ship is riding with her head to the wind, and when there is. no current; to do the fame by means of a spring; to tack or wear a fhip; to lie to, or to difpofe the fails fo that they may exacly counteract each other; and to lie to, in a gale of wind, under any fail whatever. As this laft manoeuvre is feldom practifed but when the winds are violent and contrary, there is fcarcely any operation of this kind which is not liable to failure: M. Bourde has therefore endeavoured to remedy, thefe defects, by difcuffing each feparately, and pointing out the methods which are leaft fubject to fuch inconveniences. His next concern is to direct the feaman how to chase a ship fo as to come up with her in the shorteft poffible time. Several mathematicians have treated of the curve of pursuit, or that track which one body muft purfue, under certain circumftances, to come up with another; but few or none of their fuggestions are applicable to fhips at fea. M. Bourdé fhews that, in chafing to windward, the chafing ship ought to tack as often as he brings the chafe on her beam. This has, indeed, been fhewn before by L'Hofte, and others; and it is faid that old Admiral Barnet was the firft who practifed it. In chafing to leeward, he directs us to keep the chafe always on the fame point of the compafs that he was on when firft feen. Directions are added, in both these cafes, for the fhip which is chafed. His next object is boarding; under which head he gives ample inftructions for boarding to windward, and leeward, when you come up with the chase on a wind; when going large, and when the fhip to be boarded is at anchor: but notwithstanding this useful work has now been twenty-four years in the hands of its Author's countrymen, we do not recollect to have heard of many exploits of this kind being performed by them in the courfe of the laft war! His inftructions for avoiding this terrible terrible mode of attack are equally good, and fhew him to be a moft excellent feaman. This part is concluded with rules for coming to an anchor under various circumstances. In the third part, M. Bourdé treats largely of the mafting of veffels, and contends earneftly, that fhips of war are generally much over-mafted in the French fervice: we have heard very good judges of the matter fay the fame of our own; but we believe the practice is ftill purfued in both fervices. As this, however, is a point of great importance, he shall speak for himfelf*. The proper height which ought to be given to the mafts of a ship is a problem which ftill remains to be refolved among builders: fome contend for more, fome for lefs; but the moft skilful among thefe gentlemen feem not to have paid fufficient attention to the folutions and determinations which are contained in M. Bouguer's treatife on this fubject. It appears, on the contrary, as if they had made a point of deviating, as much as poffible, in this refpect, from true principles, that they have been continually increafing the height of their mafts, notwithstanding they were much too high before, as the learned author, just mentioned, has afferted. And experience, confirmed by numberless obfervations repeatedly made by me, has convinced me that as foon as a fhip begins to lie down, her rate of failing diminishes in the fame proportion that her inclination increases. Neither am I the only perfon who has made thefe obfervations: feveral officers, unknown to me, have verified the fame principle on board different veffels, at different periods of time, and on all the various courfes which are termed oblique with refpe&t to the direction of the wind. As I had no fhare in these experiments, I cannot be fufpected of partiality; but as they always convinced those who made them that the prefent mode of mafting is generally too high, I fhall no longer hesitate to give the following epitome of my own experiments on the fubject. Having all the fails fet, and being hurried on by a strong gale, I ordered the top-gallant fails, the ftudding fails, and the ftay fails to be taken in, notwithstanding which the ship loft not any perceptible part of her velocity; on the contrary, I have fometimes feen it increafed, by these means, a twentieth part, even when the fhip was running from 9 to 12 knots in an hour. These trials were made with care, and I had them executed with fo much celerity, that there was no time for the wind to increafe or diminish its ftrength; and they appear to me fully fufficient to prove the neceffity of lowering the center of effort of the fails in general, and confequently all the mafts. I have repeated my experiments by augmenting the number of fails, fometimes fo far as to run the risk of injuring the mafts, and never found that the velocity increased when the fhip was more inclined; but that fhe laboured more and more; her motions became more uneafy, and her pitchings greater, although the fea was not higher than before. At other times, when the fhip has inclined pretty much, though the wind was not strong *We do not give the very words of the tranflator; but we have given. the true fenfe of the Author. This is done for the fake of brevity. enough enough to endanger the mafts, I have ordered the fails to be dimi nifhed; and it invariably happened, that when the upper fails were taken in, the ship was eafier in her motions, fteered better, and was more quiet, though the fwell of the fea remained the fame: an attention to these circumftances must not be neglected in observations of this kind, nor can the experiments be too often repeated before we venture to make a decifion. But notwithstanding I here reccommend a diminution in the height of the mafts, and, confequently, in that of the fails alfo, it is not my intention to recommend any diminution in the furface of them: on the contrary, I think it may often be advisable to increase that, on the whole. And this, in my opinion, may very easily be done, and the lofs of furface which is fuftained by diminishing the height be more than regained by increafing the width. But another advantage will be gained by this alteration: the topfails being shorter, and proportionably wider than before, in respect to the lower fails, they will not only be more easily fhaped in cutting, but the fides being formed by ftraight lines, the fails may be fet more taught, which is a very effential property, as they will, by that means, produce a much greater effect on the fhip. Again, the surface of the fails remaining the fame, while the mafts are shortened, the abfolute effect of the fame quantity of wind will be the fame, but its effort to make the fhip lie down will be lefs in proportion as it acts by a fhorter lever; and the fhip being more upright will fail with greater velocity, because her water-lines are more favourable when she is upright than when the heels. Befide, the less the plane of the fail is inclined to the horizon, the greater the furface will be which is prefented to the wind, and, of course, the greater the impulfe will be which it receives from it; all which advantages cannot fail to produce a very confiderable increase in the fhip's rate of failing, and decrease in the drift to leeward. To all thefe, another real and very important advantage may be added, that of being able to trim the fails much better, and of bracing them with greater ease and command. To all these advantages, M. Bourdé might have added a faving in the expence of mafts, and a very great one in the wear and tear of the fhip. After combating the prefent cuftom of tant mafting with great force of argument, he refers us to the treatife of M. Bouguer on this fubject, for the best rules that can be given for the mafting of fhips. He next treats of the different modes of ftepping the mafts, and fhews the advantages and difadvantages which attend each of the cut of the fails, and the mode of fetting them fo that the impulfe from the wind may be the greateft poffible: of the advantages and difadvantages of having a greater or lefs quantity of fail abroad under different degrees of wind of the fitting out of fhips: of careening and fheathing them' of the fcantling of the timbers, and the tumbling home of the top-timbers: of ballafting, lading, and rigging them; and many other particulars, equally important, but which are too numerous to mention here: and in every one of them M. 10 Bourdé Bourdé exhibits, in our opinion, great profeffional skill and ingenuity. The fourth and laft part of this work confifts of an Essay on Naval Evolutions; in which he defcribes and directs the divifion of fleets, the orders of convoys, of failing, of battle, and retreat; the methods of drawing up in order of battle, and of changing it, when occafioned either by a fhift of the wind, or the fituation of an enemy: the methods of maneuvering a fleet under all its various orders: fuch as avoiding an action, or forcing an enemy to come to one; in doubling on an enemy, or forcing his line, &c. &c. and he concludes his work with a plan of fignals both for day and night. The notes and remarks which are added from the papers of an English officer do him credit: they relate principally to those articles in which the practice of the English Navy differs from that of the French, and will be found by the English reader to be a valuable addition to M. Bourde's work. ART. VI. The Court of Requests: Wherein is defcribed its Nature, Utility, and Powers; illuftrated with a Variety of Cafes determined in that of Birmingham. By W. Hutton, F. A. S. S. 8vo. 6s. Boards. Baldwin. 1787. Ο F the general utility of Courts of Requefts, ufually called Courts of Confcience, the frequent appointment of them by the legiflature, in confequence of applications for that purpose, must be admitted as proofs; as alfo that they afford eafy and expeditious modes of relief to thofe who refort to them. On the other hand, the objections which have been brought against them by Judge Blackftone, are too important to be overlooked. This learned writer, after mentioning the evils which courts of this kind are intended to remedy, apprehends that the erecting these new jurifdictions may, in time, be attended with very ill confequences; that the method of proceeding in them is entirely in derogation of the common law, as their large dif cretionary powers create a petty tyranny in a set of standing commiffioners; and as the difufe of the trial by jury may tend to eftrange the minds of the people from that valuable prerogative of Englishmen, which has been already more than fufficiently excluded in many inftances. Blackstone, B. 3. Ch. 6. He therefore recommends the reformation of County Courts, in order to ferve the purpofes of Courts of Confcience. Mr. Hutton is a ftrenuous advocate for the courts, which are the fubjects of his book; of their utility he is thoroughly fatisfied, and of any inconveniences or dangers from them he appears to have no apprehenfion. In the court at Birmingham, he has been a commiflioner fifteen years! In many of thefe years,' fays he, I have not omitted attendance for one day. |