Page:Philosophical Transactions - Volume 004.djvu/217

 Therefore the time of the beginning, 6 h. 49 min. P. M. The first contact will appear 122 d. 55 m, from the Suns Zenith. And I am perswaded, that this Calculus doth, exhibite this Phœnomenon nearly, as it will appear unto us: And I question not, but that in and near our Meridian it will be observable, if the Air hinder not. It is an Appearance that will richly merit the accuratest of our Observations. For the Moons mean Anomaly being about 7 Sign. 11 deg. we may the better Judge by the Observation, Whether the Æquations of her Orbite be Oscillatory, or not. Nor need we scruple about the Æquation of Natural days: I have fully demonstrated the Æquations, so that I am perswaded, no one hererafterhereafter [sic] will controvert them; and I shall ere long, if God will, commit them to your and the publick censure.

I suppose the beginning of this Eclipse may, if the Air be serene, appear at London; but its Meridian being removed to the East from ours, 5 or 6 minutes, and its Latitude being less, so that the Altitude of the 90 deg. and consequently the Parallax of Longitude will be greater, and of Latitude, less: It follows, that the Eclipse will be retarded, and that only the beginning thereof, scarce to one digits Observation, will there appear; but in the North and the Western parts of England and Scotland, it will appear more fully: and in Ireland it will be visible to the middle of the Eclipse.

For the well-observing of this noble Appearance, I need not suggest the way of casting the Species of the Sun through a good Telescope of a competent length, on an extended paper, placed behind the Eye-glass so far, as that the said Species may appear at least 6 inches over; then dividing both his Periphery into 360 degrees, for the better observing the Inclination of the Cusps of each Phasis; and his Diameter into digits, and their parts by Concentrick Circles, for measuring the quantities of the obscured parts. For the measuring of time, the skilful Observer will be furnisht with good Quadrants, Clocks, or Pendulums.