altitude inftrument, and a tranfit telescope to be fixed occafionally on the cill of a window; also a time-teller, or affiftant clock, (le compteur ou valet) which may be carried about and placed near the telescope, while the aftronomical clock or regu lator is fixed in another place. This has a bell, on which the hammer strikes every fecond; but it is more ufual, and more useful, to make it ftrike only once in a minute. By this blow once a minute, it may be fet to correfpond with the regulator a fhort time before the expected tranfit; when that is over, the valet has done its office. Our Author alfo gives the manner of making obfervations, and computing from thence the errors of the clock.

We have then the method of examining the principal parts of a marine clock; of proving the fpiral fpring, that is, trying whether it gives ifochronous vibrations to the balance: the method of adjufting and fixing the weights of trying the continuance of the vibrations when the regulator is discharged from the wheels: of trying the effect of heat and cold, with and without the frame of compenfation; our Author here describes a stove for this purpose: of trying marine clocks in inclined pofitions: to find the allowance to be made when the frame of compenfation does not perfectly take away the effect of heat and cold. To this is added fome calculations founded upon our Author's theory.

However Mr. B. may have failed as a theorift, he has very great merit as a practical writer §. His defcriptions are every where clear and circumftantial; the drawings exquifitely fine, far beyond any thing hitherto published, except his own effay on clock-work. They contain not only what is called the calibre, that is the ichnography, but also perfpective views of every machine, both of the whole when fet together, and of the parts when feparated. No one who reads our Author, can be ignorant of the conftruction of his machines, or of the office of each part. Far from that jealoufy which attends narrow minds, he has communicated freely the refult of twenty years experience, and is ingenuous enough every where to confefs whatever failed of his expectations: which is almost as useful a piece of knowledge, as the account of what fucceeded. His mechanical contrivances fhow great ingenuity; his experiments, and the number of machines he has made, indefatigable induftry, prompted by no motive but reputation and the honour of his country. The diftribution of his work is judicious,

§ Perhaps what Mr. B. calls Principles, ought rather to be confidered as Maxims, either founded directly on experience, or deduced analogically from experiments. As fuch, Mr. B.'s propofitions require no mathematical demonstration-it fhould not be attempted.

but

but he does not keep to his plan: we find manual operations in the theory, and fpeculative differtations in the practical part. This occafions the fame things to be often repeated in different parts of the work.

We cannot but here exprefs our regret that no care has been taken to preserve the vast number of ingenious contrivances in Mr. Harrison's three great machines ||; nor indeed has any tolerable account been given either of the principles or conftruction of his laft time-piece, by which he is faid to have difcovered the longitude, and for which the parliament has given above 20,000 1. All that the Public hath for this money, is a very fhort and obfcure paper called, the Principles of Mr. Harrifon's Time keeper, but which in fact does not contain all the principles; a very material one being not so much as hinted at in his dark enigmatical way *. The drawings are all sections, mere lines, nothing fhewn in perfpective; fo that we may defy the moft fubtile genius to find out the construction of this timekeeper if he has not feen the parts. Nor can it be a doubt but Mr. H. made many interefting experiments in the space of forty-eight years, during which (in the words of the act of parliament) he applied himself with unremitting industry to the making of inftruments for afcertaining the longitude at fea +.

An account of these experiments, and even of several attempts that did not fucceed, with the reafon of their failure, would have been highly useful to the Public: nor had Mr. H. (as we are informed) any reluctance to the mentioning fuch attempts at the time of the public discovery of his principles in 1765. Mr. H. fhewed full as much readinefs in relating every thing he had tried, as his audience did patience in fitting to hear him. We have before mentioned the double balance as being one of Hooke's contrivances, and we think it probable the reft of those improvements Hooke fo much boafted of, and fo obftinately concealed, are to be found in thefe machines of Harrison's. These two admirable mechanics feem to have been parallels. They both grumbled for want of encouragement, when both got fortunes out of the Public. They had the fame reluctance to the imparting what they knew, and affected the fame obfcure way of talking and writing. They were equally jealous of all the world; equally morofe to thofe who could not understand their merit t, or would not take their

We are told the machines themselves are going faft to decay. Viz. That the longer vibrations of a balance moved by the fame fpring are performed in lefs time.

† 13 G. III. chap. 77, page 1473.

See Hooke's Animadverfions on Hevelius. See also Remarks on a pamphlet of Mr. Maskelyne's, by John Harrison.

part

part §. In fertility of invention and foundness of judgment, they were equalled by few, exceeded by none. In one point they differed; our modern genius, more modeft, pretended only to mechanics and mufic +, while Hooke laid claim to every invention he heard of, even to the fublime difcoveries of New, ton ¶.-But to return to our Author.

Befides this treatise on marine clocks, Mr. B. has published alfo An Effay on Clock-work, as it relates to the Purposes of common Life, to aftronomy, and to Navigation, &c. in 2 vols. 4to. with 38 fine copper plates, printed at Paris in 1763. This contains both the theory and practice of clock-work, a description of a vaft variety of clocks, and occafionally of feveral curious and uncommon tools. Our Author has tranfcribed into the prefent work much of that part of the effay which relates to marine clocks, and refers to the other parts of it frequently. Mr. B. has also published, very lately, a tract ferving to illuftrate and explain several matters relating to the theory, the construction, and the trial of fuch new machines as have been offered in France as time-keepers for difcovering the longitude at fea.

§ See the Minutes of the Royal Society. See also the Minutes of the Board of Longitude, and the Minutes of the Proceedings of the Commiffioners appointed by an A&t paffed 3 G. III. chap. 14. P. 359. See the preface to Smith's Harmonics.

The following extract from the Minutes of the Royal Society, will furnish us with one inftance of this, out of many that might be poduced :

66

August 16, 1699. Mr. Newton fhewed a new inftrument con"trived by him for obferving the moon, ftars, the longitude at fea; "being the old inftrument mended of fome faults, with which, not"withstanding, Mr. Halley had found the longitude better than the "feamen by other methods.

"October 25, 1699. Dr. Hooke faid the inftrument mentioned "laft meeting was of his invention before the year 1665, and the "use and fabric of it was declared in the history of the Royal So"ciety."

In Sprat's Hiftory of the Royal Society 1667, page 246, brief mention is made of an inftrument for taking angles, in which both objects are feen at once by reflection: in the animadverfions on Hevelius, page 55, this inftrument is particularly defcribed; but it differs materially from Newton's, in which one object only is feen by reflection. Hooke's defign was to enable one obferver only, to take distances of the ftars; the inftruments of Tycho and Hevelius requiring two: Newton's defign was to obviate the difficulties, from the motion of the fhip, in taking distances between the moon and ftars at fea. Hooke, we fee, eagerly laid claim to this invention of Newton's, though he understood neither the conftruction nor defign of the inftrument then produced before the Society.-This inftrument of Newton's is the very fame with the quadrant re-invented by Hadley, and now in conftant ufe. Phil. Tranf. No. 465.

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This

This is intended as an answer to a piece by M. Le Roy, charging our Author with purloining the inventions of Mr. Le Roy and Mr. Harrison. Mr. B. is very copious in his own vindication; and, in fome points, he retorts the charge of plagiarifm on his adversary.

We ought to apologize for detaining our readers fo long on this article; but in confidering this account of the attempts of a foreigner to difcover the longitude by a time-keeper, we could not pass over, unnoticed, the labours of our countrymen Hooke and Harrison.

ERRATU M.

L-m.

In our Appendix published last month, page 564, line 12, for in, read it.

ART. IX. The Hiftory of Jamaica: or, general Survey of the Ancient and Modern State of that Ifland. Illuftrated with Copper-plates. 4to. 3 Vols. 31. 3 s. Lowndes. 1774.

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T is a very difcouraging attempt to engage in a work that wants the striking incidents of ancient history, to give it a popular reputation: the road to fame feems narrowed against fuch adventurers, and the fhrine of avarice forbids their approach. These mortifying interdictions are no doubt the cause that we have hitherto had no precife defcription of Jamaica; those few who have ventured upon the unpromifing fubject were medical gentlemen, who humoured their own turn of mind in botanical researches, and gave very little attention to the more interesting parts of the history. Our prefent Author, as if infpired by fome local deity, enters boldly into the inmoft receffes of the civil polity; defcribes the refinements of government in the different departments of the state; marks out those enormities in the publick offices, from which commerce is oppreffed, and the planter expofed to irreparable injuries; dwells with an honeft delight upon those characters who have ftood forth the champions of their country, from our first fettling there, to the prefent time; difcriminates the true intereft of the island, and propofes many falutary meafures for improving it; enters upon a defcription of that part of the vegetable creation, which nature has entrusted to the protection of those friendly climates; and points out their relative advantages, as well with regard to trade, as to endemial difeafes. Climate, foil,. and medicinal springs fall within his notice and defcription; their nature and properties; their ufes and effects are explained and exemplified. The Author has indeed prefented us with a more finished picture of that country than has hitherto been exhibited; and we hope nis labour will be recompenfed in the confummation of his wifh; for by tranfporting Jamaica to England, he has brought the ftrangers together, in the generous REY. Aug. 1774.

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hope

hope that an intimacy may unite them in the fame affections, and the mother country feel a natural kindnefs for an adopted child, who contributes fo largely to her defence and fupport. This feems to be the only end our Author aims at; and as we are affured that he is a native of the island, and of confiderable landed property there, we are the more inclined to believe it. A liberal and independent fpirit alfo breathes through the whole work, that vindicates and juftifies our credulity. As we cannot enter on a regular analysis of fo large a work as the prefent, we fhall content ourselves, and, we hope, our readers, •with a few detached extracts from different parts of this hiftory; fubjoining fuch occafional obfervations as may naturally flow from the paflages felected.

Speaking, in his introductory difcourfe, upon colony adminiftration, our Author remarks that there hath been scarcely a writer upon the fubject, who hath not produced inftances of confummate tyranny and injuftice; and he declares that It is not an easy matter to difcredit what fo many evidences have concurred in afferting but he adds, it is very natural to fuppofe, that the luft of unlimited power, inherent to mankind, will always ravage moft licentiously in thofe fequeftered places, where the hand which fhould restrain its career is too diftant, and the reins are too much flackened by their immoderate length. Men entrusted with publick offices fo far from the mother ftate, require a chain, instead of a thread to hold them within bounds. It was for this reason, that the Romans, the moft generous of all conquerors, inftituted a means for punishing extortion committed by their prætors, or other officers, in their feveral provinces. The impeaching before the fenate, and bringing to justice, fuch offenders, was thought highly honourable; and was anxioufly coveted and undertaken, by advocates moft diftinguished in the city, for their virtues, rank and ability. We have feen (unhappily) the reverfe of this in our fyftem; and tyranny has not only been defended, but even careffed and rewarded, in proportion as it has been uncommonly daring and enormous.

The tyrant had only to call the fruggles of the oppreffed by the name of faction; and under the fhadow of this word, he could conceal their wounds, and his own guilt.

A faithful defcription of our provincial governors, and men in power, would be little better than a portrait of artifice, duplicity, haughtiness, violence, rapine, avarice, meannefs, rancour and difhonefty ranged in fucceffion; with a very fmall portion of honour, juftice, and magnanimity, here and there intermixed, to leffen the difguft, which, otherwife, the eye muit feel in the contemplation of fo horrid a group.

How unpleafing then would be the task of fuch a biography, which is to exhibit the deformities of human nature, unenlivened with any, or but too few, of its graces! Yet, I confefs, that if a writer could fupprefs the averfion which naturally rifes at the fight of loathfome objects, it would be no fmall relief now and then to paint those brighter tints of character, whofe radiance glistens through

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the