Some Inquiries and Directions Concerning Tides, Proposed by Dr. Wallis, for the Proving or Disproving of His Lately Publish't Discourse Concerning Them

Horns with the Angles of Inclination, it will be easy to those, that have exactly observed them, and that are skill'd in the higher Astronomical Calculations, to compute the true Place of the Moon in her Orbite, that so it may be compared with that of the Tables, and with that, which has been observ'd in other places, for the more precise determinating of the Difference of Meridians (that being the way esteem'd by Kepler the most certain) and for making a good Judgment of the defect or exactnesse of the Celestial Tables. Then they observe, That the Beginning and the Middle of this Eclipse hapned to be in the North Eastern Hemisphere, and the End, in the South Eastern. The first Contact (as 'twere) of the two Disks was observ'd in the Superior Limb of the Sun's Disk in respect to the Vertical Line, and in the Inferior in respect to the Ecliptick: But the Middle, and the End were seen in the Superior Limb, in respect both to the Vertical and the Ecliptick: And (what to this Author seems extraordinary) both the Beginning and the End of this Eclipse hapned to be in the Oriental part of the Sun's Disk. Lastly, they take notice, that by their Observations it appears, that there is but little exactness in all the Astronomical Tables, predicting the Quantity, Beginning and Duration of this Eclipse; Those of Lansbergins importing, That the Obscuration should be of 10. dig. 48'; those of Ricciolo, of 9. dig. 1'; and those of Kepler, of 7. dig. 30'. 16'': Again, that the Duration should be of 2 h. 2'. Lastly, The Beginning did anticipate the Ricciolan Tables by 5. minutes; the End by 23'; and the Middle, almost by 11. In the mean time the Author notes, that the Rudolphin Tables come nearest to the Truth; and withal assures the Reader of the goodnesse of the Instruments employed in his Observations, and of the singular care, he, together with his skilful Assistants, took in making them. Some Inquiries and Directions concerning Tides, proposed by Dr. Wallis, for the proving or disproving of his lately publish't Discourse concerning them. The Inquisitive Dr. Wallis, having in his lately printed Hypothesis of Tides intimated, that he had reason to believe, that the Annual Spring-tides happen to be rather about the beginnings of Febr. and Nov. than the two Equinoxes, doth in a late Letter to the Publisher, written from Oxford in Aug. last, desire, Sea some understanding Persons at London, or Greenwich, but rather nearer the Sea or upon the Sea-shore, would make particular Observation of all the Spring-Tides (New-Moon and Full-Moon) between this and the End of November; and take account of the Hour, and of the Perpendicular height: that we may see, whether those in September, or those of November be highest: And it were not amiss, the Low waters were observed too. Which may be easily done by a mark made upon any standing Post in the Water, by any Water-man, or other understanding Person, who dwells by the Water-side. It would also deserve (thinks he) to be inquired into, whether, when the Tides be highest, the Ebbs be ever lowest, &c.; (which is generally affirmed, and almost put out of question) or rather (which suits best with his Hypothesis) whether, when the Tides are highest, both in the Annual and Menstrual Periods, the Low waters be not also highest; and at Neap-Tides, the Ebbes also very low. He adds, that he should expect, that the Spring-Tides now coming, and those at the beginning of September, should not be so high, as those at the middle of September; and then lower again at the beginning of October, and after that, higher at the middle of October, and higher yet about the beginning of November (at the usual times of Spring-tides after the New and Full.) Considerations and Enquiries concerning Tides, by Sir Robert Moray; likewise for a further search into Dr. Wallis's newly publish't Hypothesis. In regard that the High and Low waters are observed to increase, and decrease regularly at several seasons, according to the Moons age, so as, about the New and Full Moon, or within two or three daies after, in the Western parts of Europe, the Tides are at the highest, and about the Quarter-Moons, at the lowest, (the former call'd Spring-tides, the other Neap-tides;) and that according to the height and excesses of the Tides, the Ebbes in opposition are answerable to them, the highest Tide having the lowest Ebbe, and the lowest Ebbe, the highest Tide; the Tides from the Quarter to the highest Spring-tide increasing in a certain proportion; and from the Spring-tide to the Quarter-tide decreasing in like proportion, as is supposed: And also the Ebbes rising and falling constantly after the same manner: It is wished, that it may be inquired, in what proportion these Increases and Decreases, Risings and Fallings happen to be in regard of one another? And 'tis supposed, upon some Observations, made in fit places, by the above-mentioned Gentleman, though, (as himself acknowledges) not thoroughly and exactly performed, that the Increase of the Tides is made in the Proportion of Sines; the first Increase exceeding the lowest in a small proportion; the next in a greater; the third greater than that; and so on to the mid-most, whereof the excels is greatest, diminishing again from that, to the highest Spring-Tide; so as the proportions, before and after the Middle, do greatly answer one another, or seem to do so. And likewise, from the highest Spring-tide, to the lowest Neap-tide, the Decreases seem to keep the like proportions; the Ebbes rising and falling in like manner and in like proportions. All which is supposed to fall out, when no Wind or other Accident causes an alteration.