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placed in every Ship that goes to Sea, to prevent "all future Inconveniencies and Miftakes about fuch Variation..
That Dr. Halley, the Royal Obfervator at "Greenwich, may be defired to affift and direct fome proper Perfon in making fuch a new Map, for 1740; and alfo to take Care, that, during the Obfervations of the Moon's Appulfes and Jupiter's Planets on the Coafts, for fettling the Longitude there, the like Obfervations of the fame Appulfes and Planets be made every clear Night at Greenwich; it being by the Comparison "of those Observations with the others made on the * Goafts, that the Longitudes of those Coasts must be determined, as all Aftronomers do well know. Laftly, It is humbly defired, that the Parlia "ment having provided 1500 l. for fuch preparatory Trials, as concern the Discovery of the ་ ་ Longitude, more than is to be applied to Mr. "Harrifon's Clock, fo much of that Sum may be applied to the providing Inftruments, and paying the Charges of proper Perfons to make the neceffary Trials and Obfervations aforefaid, as the "Commiffioners fhall judge neceffary to thofe Pur
pofes, and fuch Perfons employed therein as they fhall think to be moft able and willing to ferve "the Publick on thefe Occafions,"
When the Commiffioners had confidered of this Memorial, they unanimously agreed, that it was all right, and fit to be complied with; and that the Government ought to be at the Charges. But upon the Speaker's reading the Claufe in the Act of Par liament, which affigned 2000 /. for fuch preparatory Trials, he observed this very material and neceffary Preliminary of fettling the Coafts was omitted; and fo he, with the other Commiffioners prefent, fent out the Secretary of the Admiralty, Mr. Burchet, so tell Mr. Whifton, that "they did not perceive they F 2
had Authority to affign that 1500l. to the fet"tling of thofe Coafts; but that he muft apply elfe"where." Accordingly Mr. Burchet farther told him, that "he ought to lay a larger Memorial.be
fore the Board of Admiralty to the fame Purpose." So far however the Commiffioners did comply with his Defires, as to recommend to Dr. Halley the Care of making a new Map of the Variation for the prefent Time. Mr. Whifton then drew up the following Memorial; and altho' it was not laid before the Board, as will appear anon, yet it is not improper to infert it in this Place.
To the Right Honourable the Commiffioners for executing the Office of the Lord High Admiral of Great-Britain..
The Memorial of WILLIAM WHISTON, Humbly Sheweth,
THAT your Petitioner did, on the 24th of November last, lay before the Honourable. the Commiffioners appointed by Act of Parliament for the Discovery of the Longitude at Sea, a Memorial, (viz. that above) fetting forth the great Advantages that would arise to the Navigation of Great-Britain, from a more exact Determination of the Longitudes and Latitudes of our Coafts; < as alfo from the making anew Dr. Halley's Map of the Variation of the Magnetic Needle: The latter of which Propofals was then recommended. to Dr. Halley, and is now undertaken to be prepared for his Review accordingly. Your Peti<tioner did then defire of thofe Commiflioners, that "fo much of the Sum of 1500l. which was more than was applied to Mr. Harrifon's Clock, દ might be applied to the providing Inftruments, and paying the Charge of proper Perfons to
69 "make the neceffary Trials and Obfervations as "they fhall judge requifite to thofe Purposes, and "fuch Perfons employed therein as they fhould "think to be moft able and willing to ferve the "Publick on fuch Occafions,"
• Which Propofal, tho' it appeared every way • agreeable to thofe Commiffioners, and highly fit to be provided for by the Publick, yet did they obferve the Act of Parliament to be fo deficient, as to the fettling of the Coafts, that they thought they were not enabled thereby to grant the Money defired of them for that Purpofe; but that your • Petitioner was to make his Application elsewhere. • In confequence of which Determination, he now applies himself to this Honourable Board, and requests, that they would please to take the Scheme which he now lays before them into their serious • Confideration, and that as foon as poffible; that the advantageous Pofition of Jupiter's Planets, (by the Obfervation of whofe Eclipfes and Conjunctions the Longitudes of thofe Coafts are chieflyto be difcovered) the eight following Months, beginning with Auguft, may not be neglected. • Your Petitioner alfo begs of you to consider farther, that fince the prefent Design of fettling the Coafts of Great- Britain and Ireland may be perfected in thofe eight Month's Time, as appears by the Computation annexed, for about the Sum of 800. (but the Computation proving on Trial to be much too little, both as to Time and Expences, is here omitted) • whether fuch a Sum can
ever be more beneficially employed to the Navi- · gation of Great Britain, which is peculiarly under the Care of this Honourable Board, than it will be if this Propofal be complied with; which has not been made but upon Consultation with Dr. Halley, and other Perfons and Books proper for rendering it as complete and advantageous to. the Publick as poffible.'
This Memorial Mr. Whiston intended to lay before the Board of Admiralty, but as the like Propofal, actually laid before the Commiffioners for the Longitude, was stopped, because it was supposed the Act of Parliament had not enabled' thofe Commiffioners to do what otherwife they owned to be very fit to be done fo did the Opinion of Sit Charges Wager, that they had not properly any Power to difburfe the Money defired out of the contingent Money of the Navy, difcourage Mr. Whifton from laying it before them; altho' Sir Charles owned there had been two or three Examples of the like Disbursements formerly. But be this as it would, both he, and every body that was capable of judging about fuch Matters, ftill acknowledged, that the Propofal was very fit to be provided for by Parlia ment, in order to perfect their own Act: Accordingly he readily came into a temporary Subfcription of 50%. out of his own Pocket; as did the Speaker of the House of Commons, and Mr. Pointz (for the Duke of Cumberland) of the like Sum alfo. These were followed by the Lord Wilmington, the Lord Baltimore, and Mr. Townshend, in a Sub-fcription of 25 1. a-piece for the fame Purposes. The Receipt of this Money enabled Mr. Wbifion to prevent the Lofs of a Year, and to fupport his Defign till the Parliament impowered the Commiffioners to difburfe the Money out of the Navy-Office, as was before defired.
No fooner did Mr. Whifton receive the aforefaid Contributions, but he difpatched away certain Perfons, whom he thought qualified, to vifit the Coasts of Great-Britain and Ireland, and to make fucli Obfervations, in the Places he directed, as were The Inneceffary in pursuance of his Scheme. Atructions which he gave to Mr. Renshaw and Mr., Birkbeck, who were the Men fent, were, verbatim,, as follow.
September 23, 1740. i. First of all, adjuft your Royal Pendulum carefully, by feveral Days Obfervations, about Noon, that it may go true to the Mean-time. Adjust also your large Stop-watch, with Seconds, to go true to the fame Mean-time: And note, that if this be accurately done at the firft Station, a fmaller Matter will keep the Clock and Watch thus adjusted afterward, efpecially in the British Channel, where the Latitude is not much altered.
2. Set that Pendulum and Watch, thus adjusted, by Mr. Siffon's Inftrument for Dialling, the very firft Day afterward that you can fee the Sun; and this at any Time of the Day, (tho' the nearer Noon the better) ufing the fuppofed Latitude of your Place in the Maps. This is to be done frequently the fame Day, and will fet the Pendulum and Watch to half a Minute, or nearer.
N.B. The Pendulum and Watch muft always be adjusted, and kept to the mean, but not the ap parent Time, which Times are eafily reduced from one to another by the common EquationTable, and are to be both let down in the Journal.
3. If you then can see the Sun about Noon, take its greatest Altitude by your Quadrants. This Altitude, when you have deducted the Refraction from Sir Ifaac Newton's Table, pag. 69. of my laft Book, and allowed for the Sun's Declination North or South for the Time, from Vol. 1. p. 505–520. of Mr. Hodgson's Book, will give you the Elevation of the Equator, and its Complement the Elevation of the Pole, or Latitude of your Place.
4. The first clear Night take with your Quadránts the Altitude of the Pole Star fix feveral Times at least, at the Intervals of a quarter of an Hour, noting the Times by the Clock or Watch; correct thefe Altitudes as before, by deducting the