When it is finished, let it go for a Month or two; after which put the two _Indexes_ right one with the other, and both of them pointing just to 100. Then the Spring being wound up, keep it from Going (with the Key) till the Shadow of the Sun is exactly come to a _Meridian_ Line, which must be rightly prepared for that purpose. Then let it go till the Shadow comes just to the same Line the next Day, or rather 40, 50, or 100 Days after, (the longer the Better.) At which time enter down the _Centesms_ that the swiftest _Index_ points to, as also the _Integers_ and _Tenths_ of the slowest, (but put the last first in your Numbers) by this you will be furnished with two general Numbers, _viz._ the said Numbers pointed to, and the Time (in Hours) spent therein, to find the Hour of the Day to the Tenth of a Minute, at any time; for that Place where it was so set going, tho’ you remove it afterwards to any Distance whatsoever. Which two Numbers ought to be entered in a Book; to be used whensoever you would find the Hour of the Day. And it is to be noted, That if the Sun be not then in its Mean Motion, you must Add to, or Substract from what the _Indexes_ do Give, according to the Inequality thereof: But if you try it for one whole Year, there will be no need of either. And that what is said may be the better understood, I shall give an Example. _How to find the Hour and Minute of the Day at ~London~, by the said Movement._ Suppose it should be made for the Slowest to Revolve in about five Days, and after it has gone just two Days, the Slowest _Index_ should then point between 39 and 40, and the Swiftest to 21.5. Then both these Numbers (as set in Order) will make 3921.5. And if the Sun be in its Mean Motion (if not, you must Add or Substract, as aforesaid) then the said Numbers 3921.5 must always be the First; the said two Days, or 48 Hours, the Second; and the two Numbers pointed to by the _Indexes_, at the time for which you would find the Hour and Minute of the Day (as suppose the slow one should point to 87, and the swift one to 65.2, both making 8765.2) must be the Third; by which the Fourth will be obtained as followeth: Which Fourth Number being Divided by 12, the Remainder will be the Hour and Minute of the Day at _London_, as was required. Hours Hours. As 3921.5 : 48 :: 8765.2 : 107.18 ho. min. } Remains 11 : 10.8 hours. } Requir’d or 11¹⁸⁄₁₀₀ } And so for any quantity of time less than one Revolution.