Observations Made in Several Places, of the Late Eclipse of the Sun, Which Hapned on the 22 of June, 1666

PHILOSOPHICAL TRANSACTIONS. Monday Septemb. 9. 1666. The Contents. Observations made in several places (at London, Madrid and Paris,) of the late Eclipse of the Sun, which hapned June 22. 1666. Some Enquiries and Directions, concerning Tides, proposed by Dr. Wallis. Considerations and Enquiries touching the same Argument, suggested by Sir Robert Moray. An Account of several Books lately publish't: Vid. 1. Johannis Hevelii Descriptio Cometae, A. 1665. exorti; una cum Mantisla Prodromi Cometicci. 2. Isaacus Vossius de Nili & aliorum Fluminum Origine. 3. Le Discernement du Corps & de l'Ame, par Monsieur de Cordemoy. Observations made in several places, Of the late Eclipse of the Sun, which hapned on the 22 of June, 1666. The Observations that were made at London by Mr. Willughby, Dr. Pope, Mr. Hook, and Mr. Philips, are these: | The Eclipse began at 5h. 43' | h. | |-------------------------------|----| | diam. at 6. 00 | 5 dig. at 7. 06 | | 4 digits at 6. 07 | 4 dig. at 7. 13 | | 5 dig. at 6. 13 | 3 dig. at 7. 20 | | 6 dig. at 6. 21 | 2 dig. at 7. 26 | | 7 dig. at 6. 39½ | 1 dig. at 7. 32 | | 6 dig. at 6. 57 | 0 dig. at 7. 37 | Its Duration hence appears to have been one hour and 54 m. Its greatest Obscurity somewhat more than 7. digits. About the middle, between the Perpendicular and Westward Horizontal Radius of the Sun, viewing it through Mr Boyle's 60. foot-Telescope, there was perceived a little of the Limb of the Moon without the Diske of the Sun: which seemed to some of the Observers to come from some shining Atmosphere about the Body either of the Sun or Moon. They affirm to have observ'd the Figure of this Eclipse, and measured the Digits Digits, by casting the Figure through a 5 foot Telescope, on an extended paper, fix't at a certain distance from the Eye-glassee, and having a round figure; all whose Diameters were divided, by 6 Concentric Circles, into 12 Digits. The Observations made at Madrid by a Noble Member of the Royal Society, His Excellence the Earl of Sandwich, as they were sent to the Right Honourable, the Lord Vice-Count Broncker, are these; The Eclipse began at Madrid about 5 of the Clock in the morning, at 5 h. 35'. the Suns Altitude was 6 deg. 55'. The Middle of it was at 6 h. 2': the Suns Altitude, 15 deg. 5'. The End was exactly at 7 h. 5': the Suns Altitude, 25 deg. 24'. The Duration, 2 h. 4'. 37 Parts of the Suns diameter remained light. 63 Parts of the same were darkened. The Observations made at Paris by Monsieur Payen, assisted by several Astronomers, as they were printed in French, and addressed to Monsieur de Montmor, are these; The Eclipse began there, at 5 h. 44' 52" mane. It ended at 7 h. 43' 6". So that its whole Duration was 1 h. 58' 14". The greatest Obscuration they assign to have been 7 dig. 50 m. but they add, that it seem'd to have been greater by 3 minutes; which M. Payen imputes to a particular motion of Libration of the Suns Globe, which entertain'd that Luminary in the same Phase for the space of 8 min. and some seconds, as if it had been stopped in the midst of its Course; rather than to a tremulous Motion of the Atmosphere, as Scheiner would have it. They intimate that they took the time of each Phase from half digit to half digit, as well by a Pendulum, as by the Altitudes of the Suns Center above the Horizon, corrected by the Verticall Paralaxes and Aestivall Refractions, by which they judged, that though the Time by the Pendulum may be sufficient for Mechanicall Operations, yet 'tis not exact enough for establishing the Grounds of true Astronomy. They further conceive that the apparent Diameters were almost equal; seeing that in the Phases of 6 Digits, the Circumference of the Moons disk passed through the Center of that of the Sun, so as that two Lines drawn through the two Horns of the Sun, made with the Common Semi-diameter two Equilateral Triangles. Next, they affirm, That there was so great a Variation in the Parallaxes, by reason as well of the Refractions of the Air, which environs the Earth, as of the Alteration of the Air, which encompasses the Moon, that the Horns of the Sun, there formed by the Shadow of the Moon, appeared in all kinds of Figures; Sometimes inclined to the Vertical, sometimes Perpendicular to the Horizon, and at last Parallel; the Convex part respecting the Heaven, and the Concave, the Horizon. By the crossing (so they go on) of the Horns 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 exactness of the Celestial Tables. Then they observe, That the Beginning and the Middle of this Eclipse happen'd 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 happen'd 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 goodness 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