Errors of refracted Rays caused by the like Inequalities. Yet by this
Experiment I satisfied my self that the Reflexion on the concave side of
the Glass, which I feared would disturb the Vision, did no sensible
prejudice to it, and by consequence that nothing is wanting to perfect
these Telescopes, but good Workmen who can grind and polish Glasses
truly spherical. An Object-glass of a fourteen Foot Telescope, made by