Part 2

Is to t. c. of the Sun’s Decl.

So is t. Lat.

To s. c. of an Angle; which, if converted into Time (by 15) Gives the Hour and Minute of the Sun’s Rising from Midnight; and if Substracted from 12 ho. gives the Setting. Which shews the true Hour and Minute at the Place where you then are, either at Sea or Land.

The Second way for Solving the said Question, is by taking the Sun’s Altitude, when about 5 or 10 degrees above the Horizon; and at the same time let another Person see what Number the Swiftest Index points to, and after that the Slowest: Then put them both down as before directed, with the Day of the Month, and the Latitude of the place where you are; then have you the Sun’s Altitude, the said Latitude, and the Sun’s Declination, to find the Hour and Minute of the Day at the place required.

Now having by the said Observations and Cannons found the Hour and Minute of the Day for the Place where you are, when abroad; and by the Numbers pointed to, by the two Indexes, also found the Hour and Minute that it is at London, (if the Movement was there set going;) If you take the Lesser of these from the Greater, and bring the Remainder into Minutes, it will give the difference between the two places in ~Time~; by which you may find their difference of Longitude either East or West to a Minute, by the following proportion, (viz.)

Suppose the Difference of Time was 37 Minutes, then say,

{ Minutes of} {Minutes of} {Minutes of} {Minutes of} As { Time } : { Longitude} :: { Time } : { Longitude} { 1440. } { 21600 } { 37 } { 555.5 } {or 24 hours} { Deg. Min.} or 9 : 15.5 Required.

Which 9 deg. 15.5. min. being added to, or taken from the Longitude of the Place, where the said Movement was first set in Motion, gives the Longitude you are come into, as effectually as the Latitude is obtained by Observation, as was at first proposed. So that it is evident, that if any defect should be found in practice, it must proceed from the Vicissitude of the Air; and not from any Deficiency in this Discovery, or from the Cannons relating thereunto.

And that we may Answer all Objections, which may arise, on Account of the said Vicissitude of the Air, Motion of the Ship, Foulness of the Movement, &c. as well as render this Discovery more intelligible, we will descend to speak thereof more particularly: And,

In the first place, let Five or Six (or what Number you please) of these Movements be made; and after they have gone for a Month or two, (or if designed for the Sea, ’till within two or three Weeks of your Sailing) then take them asunder, and set them going by the Meridian Line, as before directed. And having entred down in the Book, herein after mentioned, the Day of the Month, when set going; how long it is making one Revolution; and what Number is produced, in just Ten Days Motion, (all which must be done, before you Sail in every Voyage;) Let them be carry’d to Sea, into any Latitude, (suppose 50 Deg. or Newfoundland) and at their Return bring them again to the said Meridian Line, and thereby (with the help of the Number of Days from their being first set in Motion) find the two first ~Proportional Numbers~, as before directed: Which done, enter them in a Book, peculiar to each Movement, (the Form whereof followeth) together with the Latitude, and Season of the Year in which the Voyage was made. Then will they all be fitted for a Voyage to Newfoundland, and Parts adjacent, for any such Season. And so for any other, when Tried and Entred, as now directed.

After which, send them all in a Ship bound to the Latitude of about 37 Deg. (suppose Virginia); and being returned, let the Numbers be found and entred, as aforesaid, with the Latitude and Season; then will any one, or all of them, be fitted for a Voyage, either to Newfoundland or Virginia, or any of those Parts, for any such like Season; and so for any other, when Tried and Entred as aforesaid.

This being done, send them also in a Ship, bound to the Latitude of 13 Deg. (suppose Barbados or Jamaica;) and being returned, find the Numbers, and enter them with the Latitude and Season: So will they all be fitted for these several Latitudes, (viz.) 50 Deg. 37 Deg. and 13 Deg. at such a Season: And by a like Process to the Æquinoctial, and towards the North Pole.

Upon which several Tryals, you will have so many Movements fitted for all the North Hemisphere, both for Hot, Cold and Temperate Seasons. And, by only Counterchanging the Latitudes, for the whole Globe; or at least for the Marine Parts thereof.

And to what is proposed to be Entred, in respect of Latitude and Season, you may also add the Time of its being first set in Motion after Cleansing; which Cleansing must be done only Annually, and as near as may be on the same Day of the Month; which will much facilitate the Inequality arising from its Foulness: By which all Objections will be answer’d, and the Discovery render’d compleat and perfect. Especially if a true Meridian Line be made in every considerable Port in this Kingdom, and elsewhere; for Examining the Movement at your Arrival abroad, and setting it in Motion, before your Departure. But remember, that where you set it going, from thence your Departure must be reckon’d.

And by this Method all the said Vicissitudes that may arise in respect of Latitude or Seasons, Motion of the Ship (which will be near the same in one Voyage, as in another) and Cleanness or Foulness of the Work, will also plainly appear upon Record, (by comparing one Number in the said Book with another) and will be Accounted for, and Æquated, as occasion requires: Namely, by only taking such Numbers from the said Book, to work your Proportion by, as are entred for the Latitude and Season, that you are again Arrived to, or Sailing under: As suppose into 50 Deg. in the Summer Season, then take the Number and Hours answering thereunto; and so, if in Winter, those for the Winter. By which proportionable Numbers, the said Contingencies will be truly and effectually Allowed, and the Difference in Motions justly Æquated, as was before asserted.

Note, That in this Movement, the ~Time~ is Regulated or Conformed to the ~Motion~: Whereas in former Movements, the ~Motion~ is Regulated or Conformed to the ~Time~. And this ought to be well understood, before you can rightly comprehend what is herein contained.

Now that this Movement, or Discovery, does not only differ from, but also far exceed, any that has hitherto been proposed; is evident in this (viz.) That if any former Movement whatsoever be Timed here, as usual, ~Before~ it is carried to Sea, (tho’ never so exactly) yet the change of Climate, &c. will so affect it, as to make it go False: And if you fit it there, then ’twill be also False when brought hither: But if by this Movement, and the foregoing Rules, the said Numbers be found ~After~ it is returned from such a Voyage; all the said Defects or Contingencies will be Æquated by the said Numbers only. So that it will be the same in use, as if no such Accidents did attend it at all. And this Assertion must, and will be granted, by every one that does fully comprehend the Nature and Use thereof. For altho’ this Horologe has no certain Hours or Time pre-assigned to it; yet it hath nevertheless, greater or lesser Numbers Æquated to the Variableness of Motion or Time, (viz.) If fitted to be used here in England, then it hath (or may have) one sort of Numbers (or Time) for finding the Hour and Minute, in the Summer Season; another for Winter; and a third for the Spring and Fall; one when it lyeth undisturbed in one and the same place; another (if you please) when carry’d always in a Rattling Coach. And on the other hand, if you carry it to Sea, then it has one for the Torrid, one for the Frigid, and a third for the Temperate Zones, &c. And yet still but one and the same Horologe, and but one and the same Indexes. So that all manner of Natural Vicissitudes or Contingencies whatsoever, may be Regulated or Æquated in and by the said Numbers; and consequently, the true Hour and Minute of the Day, where it is first set going, may be hereby as effectually found, as if no such Impediments did at any time or place attend it, as aforesaid.

And as for what may be suggested in relation to the Inequality between the Spring and Fusie, if any should be, it will be compensated, in that there are five or six Windings up of them, to one Revolution in the Horologe. So that there is nothing wanting to compleat this Discovery, but to put it into Practice: And seeing the Charge and Trouble is very Inconsiderable; and the Legislature by Act of Parliament, hath been graciously pleased to Incourage hereunto, it is thought expedient to make this publick Proposal, viz.

That if any one Person is willing to Engage in this so Noble an Enterprize, he will be readily received as a Partner, on such Conditions as may be Reasonably Concerted therein.

You may hear of the Author at Mr. ~Burleigh~’s in ~Amen-Corner, London~.

MEMORANDUM.

1. All Departures must be reckon’d from London, if the Movement was there Set going.

2. That wheresoever they are Set going, there must be a large and exact Meridian Line prepared by a Perpendicular, set up in an Horizontal Circle, as is Mathematically taught, &c.

3. That an Equal time be spent in Winding it up, as near as possible; for which no time need be allowed, if Equated for 10 or 12 Months; because the time required will be the same for the same time, and greater for a greater, &c.

4. That the said Movement be carefully kept in one and the same Temperature of Air, as near as possible.

5. That after this Movement is fully proved, if it should not (by reason of any sudden change of Air) agree to a Minute, yet it ought not in this respect to be altered or much regarded, because the moistness of one Month, may compensate the Dryness of another: So that by such time as you are arrived to the end of your Voyage, the Movement may even Rectifie or Correct it self.

6. It is to be noted, That if the Sun comes too soon to the Meridian, it will also come too soon to the Horizon; and therefore, Watch too fast, or too slow, must be Added or Substracted, as aforesaid.

7. That it be always wound up, as near as may be, at one certain time of the Day, (viz.) if at Sea, about Twylight, or Break of Day, as may be thought expedient. And if it should happen to be omitted, so long as to stand still; you must not set it going again, but by taking it assunder, and putting the two Indexes together, and bringing the Movement to the Meridian Line, as at first directed. Therefore when at Sea be careful of such Omissions.