( %6\ )

z. The cxact measures of the Heigbts os every utmost Higb-fVatcr and LovsWater srom one Sprtng-Tide to another.

4 The exact Heigbts os Spring-Ttdes and Spring-Ebbt.

In order to ali which this following apparatus is proposed to be made use os.In forne convenient place upon a Wall, Rock, or Bridge, &c. Let there bean Observator/ standing as near as may be to the Brink cis the Sea, or uponforne Wall; and is it cannot be well placed iust wherc the Law-Uittcr is, theremay be a Channel cut srom the Lovv-Water to the botrom os the Wall, Rock,&c. The Obf rvatcry is to be raised above the Higb-Water 18 or ao Foot,and a Pump of any reasonable Dimension, placed perpendiculari/ by theWall, reuching above the High-Water as high as convenienti/ may be. Up-on the top of the Pump a Pulle/ is to be fastr.ed, for letting down into thePump a piece of floaring Wood, which as the Water comes in may Rise andFall with it. And because the Rstng and Ealhng of the Water amounts to 60or 70 Foot, the Counrerpoise of the Weight, that goes into the Pump, is tohang upon as many Pulleys, as may ferve to make it Rise and Fall within thespace by which the Height of the Pump exceeds the Height of the Water. Andbecause by this means the Counrerpoise will Rise and Fall slower, and con-sequenti/ by less proportions, than the Weight it seif, the first Pulley mayhave upon it a Wheel or two, to turn Indexes at any proportion required,fo as to give the minute parts os the Motion, and Degrees of Risings andFallings. And because if the Hole, by which the Water is let into the Pumpbe as large as the Bore of the Pump it seif, the Weight that is Raised by theWater, will Rise and Fall with an Undulatiori according to the Inequality of theSea’s Sursace, ’twill therefore be fit, that the Hole, by which the Water enters,be lese than hall as bigg as the Bore of the Pump ; any lnconvenience that mayfall thereupon, as to the Periods and Starions of the Floud and Ebb, not beingconsiderable.

5. To obferve the Position and Strength of the Wind-, the state of the Wea-tber\ The Heights of the Barometer, Thermometer, Hjtgrofcope ; and the Moon ijlge , and Place in ali respttsts.

IV. 1. The true Time of the Tides at all times of the M on, is very rude-ly and stightly reckoned up by most Seamen and Astronomers, most of themreckoning,as if the Moon bJng upon such a sct Point of the Compafs (as the Sea-men calls it) or fo many houn past the Meridian (as the Almanack-Makersreckon ) it were High-Ttde in such and such a Port at all Times of the Moon.And thus they reckon the Tides every Day to differ constanti/ 48 min. As forInstance; a South-West Moon makes a Füll Tide at London , that must be un-derstood that it is High-Ttde at London, when the Moon is 3 hours past theMeridian. Now this is true indeed at the New and Füll Moon, but not atother Times of the Moon, which few take any notice of: Only Mr. Bookerhad wont to give this Caveat, that about the first and last Quarten of theMoon, the Neap-Ttdes did not flow so long as the Sprmg-Ttdes by one Point ofthe Compasr, but he gives no Rule to proportion the diftcrence.

Tides oijtrvtdst London:Mr. Hen. Phi-lips. n. j«.P-656.

But