y3 OF THE DISCOVERIES OF

one Zachariah Jansen, a spectacle-maker of Mid-dleburgh in Holland, being at play in theirfather’s shop, happened, by chance, to place aconvex and concave glass in such a manner, thatin looking through them at the weather-cock ofthe church, it appeared to be nearer, and muchlarger than usual. The surprise they expressedat this circumstance, exciting their father’s cu-riosity, he examined the same object himself,and finding what the children said to be true,improved the hint, by fixing the glasses upon aboard, that they might be always ready for ob-servation.

A discovery attended with so many obviousadvantages, could not long be kept a secret;the news was soon conveyed to all the learnedthroughout Europe. Galileo was at Venicewhen he first heard of the invention ; and beingonly informed, that by the combination of twoglasses, the apparent magnitude of objects mightbe considerably augmented, he soon discoveredthe whole secret. Instead of the board employedby Jansen, he made use of a tube, and, at his firstessay, produced an instrument which made thediameter of objects appear three times greaterthan to the naked eye. At his next trial hemagnified the diameter of an object about eighttimes, and soon after this thirty times ; which isnearly the greatest perfection, that this kind oftelescope is capable of.

Thus