an object worthy of the public attention and encouragement, many have applied their studies and endeavours to discover that great and important secret.

Having acquired a competent skill in the grounds and principles that led thereto, and humbly presuming that, through God's blessing on my long study and application, i have found out, by certain tables and calculations, such a method as may render it not only practicable, but intelligible to common understandings; I pray leave to lay the same before your lordship.

And as yourlordship must be acknowledged the best judge of the justness as well as the use of what I have to offer, I shall humbly presume to submit the same to your lordship's examination; and to entreat your protection and patronage, if it shall appear to be deserving of that honour.

I am now in the last stage of life, being above 80 years of age; and can hardly expect to live long enough to see the success, should the scheme, through your lordship's approbation be carried into execution. But it is no small concern to me to think a secret of so general use should die with me, and be lost to my own country, or that after my decease it should be communicated to foreign nations, in case it meet not with a favourable reception here; and so all that labour and pains be lost which for so many years I have been taking, to promote the benefit and advantage both of his Majesty's nary, and the whole British navigation in general.

I pray leave to inclose the printed proposals: and humbly presume to hope I may be admitted to the honour of your lordship's presence, in order to answer or explain such inquiries as your lordship may think proper to make; and, in the mean time, I flatter myself with hopes, that your known candour and goodness will receive with favour the well-meant endeavours, as well as person, though almost worn out with

age

and the want of the necessaries and comforts of life, of, my lord, your lordship's most obedient, humble servant,

Z. WILLIAMS.

LETTER VI.
To Mr. Zach. Williams, at the Rainbow Coffee-house on

Fleet-Bridge, London.
SIR,

Greenwich Park, Nov. 5, 1751, DR. BRADLEY has ordered me to let you know that he VOL. III.

L

will meet you at the Rainbow coffee house, on Fleet-Bridge, between eleven and one o'clock on Thursday next, if he is not prevented; but if you do not see him then, he will let you know further. I am your humble servant,

JOHN BRADLEY,

LETTER VII.

To Doctor Bradley.
Rev. SIR,

Nov. 11, 1751. I HAD not the good fortune to receive Mr. Bradley's letter of the 5th. instant till to-day, though I did not miss to inquire daily at the coffee-house; therefore hope you will pardon iny not keeping the appointment, which gives me the more uneasiness, as I am informed that you took the trouble of calling upon me there. Let me then again beg the favour that you will appoint another meeting, either there or elsewhere, and you shall be duly waited upon by,

Rev. Sir, &c. You will oblige me very much, Sir, by sending me a linę in answer by the bearer.

LETTER VIII.

To Mr. Zachary Williams. DR. BRADLEY intends to call at the Rainbow coffee-house about eleven o'clock on Thursday next, viz. Nov. 21,

LETTER IX.

To Doctor Bradley.
SIR,

Nov. 26, 1751. The lords of the Admiralty have been pleased to refer my system of the variations to your examination; and you have now in your hands the final event of the study and labour of a long life, lost, without your candour, in a fruitless application. I am not soliciting you, by this warm address, to any favour inconsistent with honour, with science, or with truth; nor intreat any thing farther than such expedition as my age now makes necessary, and such a representation to their lordships as may incline them to consider my scheme as worthy of their attention, and to favour me, like others who have laboured in the same design, with such encouragement, patronage, and assistance, as may enable me to prosecute my experiments and complete my tables.

Z. W.

LETTER X.

To the Lords of the Admiralty.

MY LORDS,

Dec. 10, 1751. As my proposal for settling the variation has had the honour to attract the notice of your lordships, and to be referred to the Professor of Astronomy, I presume to entreat one more act of indulgence; which I Aatter myself that your lordships known skill in philosophy and navigation, and that curiosity which science always produces, will incline vou to grant.

I have, by the industry of many years, prepared an instrument which may be called an epitome or miniature of the terraqueous globe. It shews the variation of the variations for two hundred years, and consequently revolves by inspection, without any calculus or table, all questions relating to the sailor's needle. If the year for which the variation is required, with the longitude and latitude of the place, be given me, I can iinmediately shew the variation; if the year, latitude, and variation, be given, I can shew the longitude. As I am conscious to myself of no fraud, I would not decline the severest trial before men who know to how much uncertainty the utmost accuracy which experiment and observation have yet attained is exposed, and who can make the just allowances for the slowness and hesitation of a man now sunk with disappointments, and overborne with more than eighty years. I, therefore, humbly petition for the privilege of exhibiting before your lordships the effects of my instrument, and intreat that such questions may be prepared as shall seem to your lordships sufficient for a trial.

I shall gladly attend at any time and at any place; but hope that your lordships will pardon me, if, in my eightythird year, I am desirous that nothing which I am to perform may be long delayed. I am, my lords, with great submission and respect, your lordships most humble and most obedient,

Z. WILLIAMS,

LETTER XI.

To the Lords of the Admiralty.

MY LORDS,

Jan. 2, 1751-2. I HAVE again taken the liberty to attend your lordships, to return you thanks for the notice with which you have been pleased to honour my proposal, and to entreat the continuance of your favour.

I beg leave to remind your lordships, that the only test of my tables, and of the system on which they are formed,

experience. Mathematicians, mere mathematicians, are apt to be misled by the prejudices of theory, and perhaps sometimes by those of rivalship. They have no immediate interest in the discovery unless it be made by themselves, and therefore are not very forward to find it in the hands of another. For these reasons, I entreat your lordships to take it into your own examination, or to refer it to some able and candid navigators, that I may have the honour of the highest approbation, or at least the satisfaction of being condemned by unexceptionable judges.

I am, my lords, &c.

LETTER XII.

To the Lords of the Admiralty,

My Lords, I HAVE been long hindered by sickness from attending on your board; but presume to hope that your lordships are not now less willing than before to examine and consider my scheme of the variation, and therefore once more implore the favour of a candid trial. If I might be allowed to propose my own judges, I should desire to be tried only by navigators, as the only persons interested in the success of such undertakings, or rather almost the only persons capable of judging, who have not an interest in opposing every scheme but their own. I am, my lords, your lordships most obedient and most humble servant,

Z. WILLIAMS,

LETTER XIII.

To Lord Anson.

MY LORD, I PRESUME once more to entreat your lordship's attention to my scheme of the variation of the compass.

As all the means hitherto offered for the discovery of the "longitude are evidently defective, and all the hypotheses of the magnetic variation, yet proposed, confessedly erroneous; I cannot but hope that your lordship' will be pleased to favour a scheme, by which it is conceived that the variation will be complete, and the longitude, by easy deduction, ascertained; since you know, not only by theory, but by long hazardous experience, how much would be added by this improvement to the safety of navigation.

My scheme is easily examined. By an instrument which I have constructed, I shew the variation of any given latia tude and longitude ; and, as I proceed systematically, a short trial will be sufficient to decide the merit of the performance; for, if the instrument is found to agree with such observations as your lordship shall think worthy of credit, at a few places remote from each other, it may be credited for the interjacent places; it being scarcely to be imagined that an instrument can be constructed upon principles so as to be right in some places without being right likewise in others; as a clock, which we find right at seven and nine, can hardly be conceived wrong at six, eight, or ten.

I humbly entreat that your lordship will be pleased to allow me to attend you with my tables and instrument, which many gentlemen of eminence, both in the theory and practice of navigation, have thought worthy of their notice, for the curiosity of its construction; but which, I believe, your lordship will find to answer more important purposes. I am, my lord, your lordship's most obedient and most humble servant,

Z. WILLIAMS.

P.S. My lord, I have taken the liberty to trouble your lordship with a copy of my last letter directed to the Hon. Board of Admiralty, which has not yet been honoured with