what motion can you imagine the earth to have to be little enough to swell the waters five nay ten foot upon those shores where the Seas are two or 3000 miles or more over as they commonly are I am in the mind you will say and you may safely do it that this motion must be so little as to be almost altogether insensible So that though I have made a great many words about it and talkt of six hours motion from east to west and west to east yet when you have well considered the matter you may without any Prejudice to your Judgment very well suppose the Earth always to have had this motion though you knew it not As shall be abundantly confirmed to you by all that follows for The Moon giving the Earth this Motion the Tides must fall exactly so many Minutes later as the Moon doth THe other Motions of the Seas may as well be thought to depend upon the Motion of the Sun as Moon butin this the Moon seems to have all the sway and has so far outrivald the Sun that men in all ages have willingly assign'd the Empire of the Ocean to the Moon upon the account of the most exact agreement that is found between the Moon and Seas in this Motion of Retardation which is thus The Moon comes later to the same point of the Heavens one day with another by about forty eight minutes and the Tides observe the same When the Moon is in Conjunction with the Sun it is always high water at London-bridge at three a clock but now the same Tide will fall later every day as the Moon doth so that when the Moon is in Quadrature with the Sun the same Tide will fall six hours later that is at nine a Clock And so every seven days the same tide will fall later by six hours till the Moon is in Conjunction again and then the same Tide will fall out at three a clock as before If the Moon comes later to the same point of the Heaven 10 15 or 20 Minutes this day as it sometimes falls out so then the day before the Tides observe the same all the World over and that so precisely that no rule can be given to know the time of high-water but by knowing the true time of the Moons coming to the South And which is more if strong winds keep back or accellerate the Tides as oftentimes it happens half an hour or more yet the very next Tide if it be a calm shall observe the due time it should have done notwithstanding this interruption Then the question may well be askt whether or no the Seas Universally may be made thus exactly to keep time with the Motion of the Moon by any other ways or means whatever then by the motion of the Earth but no man can doubt but that if the Moon give the Earth motion after the manner that I have supposed it but that the Seas must observe the same even to a minute of time For if the Moon shall be South-east South-west North-west or North-east at which points the Motion of the earth and seas from East to West or West to East always begins this day at 12 a clock if to morrow the Moon comes later to these points 20 or 30 minutes its certain that the Motion of the Earth cannot begin till then and by consequence it must be high water so many minutes later This is so manifest that to say more would be needless And therefore I shall now let you know By what means the Motion of the Earth and Seas are abated and increased every seven days I Said before that the Moon and Sun by a powerful Magnetick attractive Vertue gave the Earth Motion I shall now add That by reason of the exceeding swift motion of the Moon the Sun sometimes comes to be so posited as directly to oppose the Moon in the Motion and sometimes to assist with all his forces But that you may the better understand what I say and at the same time fancy to your self how much the Sun contributes to or impedes the Motion as he comes to be every day diversly posited I will now examine how much the Sun may be concerned in the Action which may easily be gathered from this That when the Moon is 90 degrees from the Sun the Sun then directly opposes the Moon in the Motion and yet then the Tides here at London commonly rise about 12 foot At new and full Moon the Sun lends his utmost Assistance and then they rise about 16 foot now if when the Sun directly opposes the Moon the tides rise 12 foot and whenhe assists with all his forces they rise but 16. its certain that if the Sun did neither hinder nor assist the Moon alone would give the Earth so much motion as should constantly make the Tides rise here 14 foot So that the Suns interest can be but as two to 14. I do not pretend to be precise in this for perhaps there may be especially at some times of the year more then four foot difference between the Neap and spring Tides here and it may be the Neap and Spring Tides rise not commonly so high as I speak of but this is not so far from the Truth but that it may serve to make a pretty near Estimate Then now if you Understood after what manner I suppos'd the Earth was mov'd and at what points it had it's greatest Motion You will easily know how that motion comes to be abated or increast which is thus Suppose the Moon in the Horizon East and in Conjunction with the Sun this day then the Tides must be at the highest for now the Moon and Sun being carried round the Earth in the same Point they with their United forces must give it as great a motion as at any time they can For the next day it will be three quarters of an hour later before the Moon reaches the Horizon and then the Sun will be about 12 degrees above it So that this day when the Moon shall be South-east the place of greatest advantage of giving the Earth motion the Sun will be 12 degrees nearer the Meridian at which point the Sun cannot altogether so powerfully assist the Moon as the day before when they were both at the same time in the South-east Point So that this day the motion of the Earth is a very small matter abated And for the same reason the Motion every day abates till the Moon is in the quarter For about three days after change when the Moon shall be in the Horizon the Sun will be 45 degrees above it then this day all the time the Moon is moving from the Horizon to the South-east the Sun is moving from the South-east to the Meridian in all which points especially near the Meridian the Sun but faintly assists the Moon and in the meridian not at all But the next three days the Sun does not only less assist but every day more
then other opposes the Moon in the motion For about five days after Conjunction when the Moon shall be in the Horizon the Sun at the same time will be about 60 degrees above it Then this day when the Moon is South-east the Sun will be declined 12 degrees West from the meridian So that all the time the Sun was moving from the meridian to that point The Sun opposed the Moon by drawing from the contrary point of Attraction The next day the impediment will be greater and when the Moon shall be in the quarter or 90 degrees from the Sun then will the Sun directly oppose the Moon all the time of the motion For then when the Moon is in the Horizon the Sun must be in the Meridian so that all the time the Moon is moving from the Horizon to the south-east the Sun is moving from the meridian to the south-west and so directly opposes the Moon with all his forces The Sun having in all those points the same advantage of giving the earth Motion from West to East that the Moon has of giving it motion from East to West now if the Sun did attract with equal force the Earth must this day be without motion but the Moon by reason of her nearness being much more powerful gives the Earth motion notwithstanding this Opposition Then now the Tides are at the lowest the Earth having now the least motion it can at any time have For now for the same reason that the motion was abated from the Moons being in Conjunction till she was in the first quarter it will now be increast till she is in Opposition The next day after the quarter when the Moon shall be in the Horizon the Sun will be 12 degrees West from the meridian then this day when the moon shall be south-east the Sun will be declined 12 degrees from the south-west at which point the Sun cannot so much impede this motion as the day before And now every day the Impediment will be less and accordingly the motion of the Earth and Seas will be increast but especially three days before the moon comes into Opposition for then the Sun does not only less oppose but for some part of the time every day more then other assists the moon in the motion And when the moon shall be in opposition the motion will be the same it was when in Conjunction for then when the moon is in the Horizon east the Sun will be in the Horizon West and as the moon rises above the Horizon and gives the Earth motion from East to West the Sun at the same time declines beneath the Horizon and assists the moon in the motion altogether as powerfully as when in Conjunction As the moon attracts or turns up the eastern side of the Globe the Sun at the same time pulls down the VVestern side which is the same thing as if they had been both in the same point and the motion will be as great and the Tides as high as at the new moon The same order is observ'd till the moon comes into Conjunction again for as the motion was abated from new moon to the first quarter so now for the same reason and after the very same Proportion it will again be abated till the moon is in the last quarter and then increast as before for the next seven days c. Now let any man that takes pleasure in these things consider well with himself how much every day the motion of the earth ought to be abated or increast allowing the Sun to have such an interest as I spake of before and I dare promise him all the satisfaction in it can be expected for upon Examination he shall find the increasing and decreasing of the Tides to corrospond as exactly with it as he can desire and much more excellently then I can express it Three Days before new and full moon you shall find the sun very aptly plac't to assist the moon in the motion and acordingly you will find the Tides to increase Three days after new and full moon the sun not much less assists the moon tho every day less then other then upon the same day and then you will find the Tides to decrease but leisurely Three days before either of the quarters you must think the sun notably impedes the motion the Tides then decrease a pace Three days after the quarter the Tides increase but slowly the sun those days less opposing but not at all assisting the moon There is yet a fourth motion of the seas that is That these Spring Tides are made to increase and decrease every quarter of a year THis motion of the Seas has not I think been much taken notice of here only Learned men have observ'd that the spring Tides are usually higher in March and September then ordinary But in the Mediteranean Sea it has been known long since that the spring Tides are constantly lower when the Sun is in either of the Tropicks and higher when in the Equator and he that shall observe it upon any shore that lies open to the Ocean in any part of the World I believe will find it so but this place is by no means fit for these inquiries for in December Land-floods many times makes the Tides higher then usual at other times they are pestred with Ice and that keeps them back besides strong winds at Sea often makes the Tides higher or lower then Ordinary when perhaps its calm here And then in June tho the spring Tides are lower then then usual yet it has been thought to be only for want of fresh water coming down so plentifully as at other times and indeed reason and Experience tell us that when Land-floods happen at the new or full Moon the spring-tides must be and are then higher then at that time of the year they are accustomed to be and by Consequence when the Rivers are empty the Tides must be and are then lower But then it s well known that the waters in European Rivers are usually lower in September then in June and yet the spring-tides are then commonly highest but by reason of the aforesaid frequent Interruptions this has not been taken notice of though its discernable enough here to a curious observer And the Reason why the spring-tides are higher at these times then Ordinary is very plain and may in a few words be dispatcht For suppose the Moon to be in Conjunction with the Sun in the first degrees of Cancer they now in their diurnal motion describe the least Circle except when in Capricorn and then it is the same about the Earth and then must give the Earth the least motion This you cannot question for if you were to give a Wheel motion upon its Axis you would not lay your hand upon the Nave or near it but upon the Rim the greatest Circle since you might with using but the same strength at the Rim give it a greater motion then in any lesser
circle 'T is the same with the Sun and Moon about 14 days after this the Sun will be in the middle of Cancer and the Moon about the middle of Capricorn in Opposition with the Sun which is the same thing as if they were in the same circle and describe circles so much greater and by that advantage give the Earth a greater motion so that this spring tide must be a little higher then that that happened 14 days before And so every time the Moon shall be in Conjunction or Opposition with the Sun they will yet describe greater circles and by that means give the earth a greater Motion and accordingly the spring-tides will increase till the Sun has reacht the Equator And then being carried directly over the Body of the Earth in the greatest circle they must needs be thought to give the Earth and Seas the greatest motion So that now the spring-tides are at the very highest for now they will for the same reason decrease again till the Sun is in Capricorn and the next quarter increase c. And this without doubt is the only cause why the spring-tides are higher in March and September and lower in June and December I have endeavoured to inform my self how much the spring-tides are higher when the Sun is in the Equator then when in the Solstices and by the nearest Observation I could make here at London there is the difference of near two foot but I am not so well satisfied in it as I desire It will not be amiss to give you notice here that you shall hardly meet with two men that agree at what time the Spring Tides are at the highest I mean those Spring Tides that happen at New and Full-Moon some saying upon the day the Moon is in Conjunction or Opposition some the next day others will have it the third Tide after by which it should seem the time is not fixt I am in the mind that for one half of the year the Tides may increase a day or more after Full and Change but not the other half That is from June to September and from December till March my reason for it is this in these quarters the Sun is returning from the Tropicks to the Equators and then though the Sun a day after full and change do less assist the Moon in giving the Earth motion then upon the day yet it is so very little less that the disadvantage is more than recompenc'd by the Moons discribing the day after having a very swift motion a greater Circle about the Earth As the Sun goes from the Equator to the Tropick it is quite contrary for then the day after full and change the Moon describes a lesser Circle than the day before and then the Tides should not increase after New and Full-Moon at least not so long I have made some agreeable observations about this but have not had time for a strict inquiry though I have long thought of it Those that live near this or any other River that Ebbs and Flows may easily inform themselves whether this be so or no. But now besides these alterations of the Seas it must follow upon this motion of the Earth first that when the Tides rise highest they must fall lowest Secondly That the Tides in all Seas must set East and West and Thirdly That the motion of the Seas must begin at the same time all over the World The first of these you may at your pleasure observe and you shall alwayes find that the highest spring Tide makes the lowest Ebb. And all experimene'd men know the Tides set directly East and West upon all the utmost Eastern and Western Shores in the World And I think that Learned men are agreed that the motion begins at the same time in all Seas Thus much is certain that when the Moon is South-west or in the opposite Point of the Heavens that is North-east it is alwaies high-water upon all the utmost open western Shores of Europe and Affrica from Nova Zembla to the Cape of Good-hope And that when the Moon is South-east or North-west it is high-water upon the utmost Eastern Shores of America So that when it is high-water upon the first named it must be low-water upon the other Shores When they have the first of Ebb upon the Western Shores of Europe and Affrica they must have the first of Flood upon the opposite Eastern Shores of America By which it is plain that the motion begins at the same time in all these Seas and that what we call the Ebbing and Flowing of the Sea is nothing but the falling of the waters from off the Western upon the Eastern Shores and the same back again every 6 hours But further when it is high-water upon the Western Shores of Europe and Affrica it is high-water at the same time upon the Western Shores of Italy and upon the Shores of Syria at the bottom of the Mediteranean Sea and take good notice of it when it is high-water upon those Shores it is low-water at Venice and on the contrary Now this I take to be a very forceable argument to prove the motion of the Earth as I have supposed it and then the motion must begin at the same time in all Seas for it is unconceivable how this should otherwise happen but if you shall fancy the Terraqueous Globe to have a little motion from West to East you will then say that it must make high-water upon all the first named Shores and low-water at Venice But then let the Eastern side be turned up and it must make high-water at Venice and low-water upon all the other Shores The instances that may be taken out of this and other Seas to confirm this motion of the Earth are every where so many and so obvious that they cannot escape your notice if you will but take the least pains to inquire into these things Nor can you I think meet with any thing that shall seem to contradict it A reason now should be given Why upon some Shores they have almost no Tides when upon others they have great and almost incredible Floods I will onely name some of those places that are most remarkable for great Tides or the contrary without attempting to give a reason why it is so being almost confident that when you have observed those places well you will say that the Earth having such a motion it must of necessity be so I will begin in the North parts of Europe In some Bays upon the Shores of Nova Zembla it Flows 12. or 14 foot but in some places upon the Neighbouring Shores of Lapland they have no Tides at all and where they have most which is as I remember near the Bay of St. Nicholas one two or three foot Pet and Jackman searching for a passage by the North east to India found the waters in some of the Bays upon this Coast to be black and like a standing Pool without Motion Note that there are