Page:History of the Royal Society.djvu/272

 Of the variety, and excellence of the Instruments, which this Age abounds, for their help in Philosophical matters, I have already discoursed in the former Part. I will now go on to mention those new ones, which they themselves, or some of their Members, have either invented, or advanc'd, for the ease, strength, and direction of their Senses, in the motions of Nature, and Art: of this kind are these that follow.

An Instrument, for finding a Second of Time by the Sun: another for finding the Celestial Refractions.

Three several Quadrants made after three new contrivances, which though they are riot above eighteen Inches in Diameter, and so are manageable in any Window, or Turret, are yet far more exact than the best, that have been hitherto us'd, for Astronomical Observations, or taking Angles at Land.

A new Instrument, for taking Angles by reflection; by which means the Eye at the same time sees the two Objects, both as touching in the same point, though distant almost to a Semicircle: which is of great use for making exact Observations at Sea.

A new kind Back-staff, for taking the Sun's Altitude by the Shadow, and Horizon: which is so contriv'd, that though the Shadow be at three foot distance, or as much more as is desir'd, yet there shall not be the least Penumbra: and the Shadow may be easily distinguish'd to the fourth part of a minute.

A Hoop of all the fix'd Stars in the Zodiac, for the speedy finding the Position of the Ecliptic, and for knowing the Extent of the Constellations.