Page:Philosophical Transactions - Volume 004.djvu/56

 if it be going; if not, set it a going, and put the Indexes, at what hour, min, and sec, you please. Let them goe till Sun-set, and when the Body of the Sun is just half under the Horizon, see, what hour, min. and sec. the Indexes of the Watch point at, and note them too; and reckon, how many houres &c. are Pass'd by the Watch between the one and the other: which is done by adding to the Evening-Observation the hours, &c. that the morning-Observation wanted of 12. or 24. in case the Hour-hand hath in the mean time pass'd that hour once or twice; otherwise the difference only gives the time. Then take the half of that number, and add it to the hours, &c. of the morning-Observation, and you shall have the hours, &c. which the Watch did show, when the Sun was in the South; where unto add the Æquation in the Table belonging to that day, and note the summe. Then some days being pass'd (the more the better,) you are to doe Iust the same: and if the hour of this last day be the same, that was noted before, your Watch is well adjusted; but if it be more or less, the difference divided by the number, elapsed between the two Observations, will give the daily difference. And if you will, you may let it rest there, or otherwise, removing the lesser weight of the Pendulum you may adjust it better. Rh