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HISTORY OF PHYSICAL ASTRONOMY.

bodies, and dispose them in such order with respect to the eye and theobjects, that the rays shall be refracted and bent towards any place weplease; so that we shall see the object near at hand, or at a distanceunder any angle we please. And thus from an incredible distance wemay read the smallest letters, and may number the smallest particles ofdust and sand, by reason of the greatness of the angle under which wemay see them ; and on the contrary, we may not be able to see thegreatest bodies close to us, by reason of the smallness of the angle underwhich they may appear ; for distance does not affect this kind of vision,except by accident, but the magnitude of the angle does so. And thus aboy may appear to be a giant, and a man as big as. a mountain, for asmuch as we may see the man under as great an angle as the mountain, andas near as we please; and thus a small army may appear a very great one,and though very far off, yet very near to us, and the contrary. Thus also,the sun, moon, and stars may be made to descend hither in appearance,and to be visible over the heads of our enemies, and many things of the likesort, which persons unacquainted with such things would refuse to believe.” *

The following passage, extracted from the preface, written by ThomasDigges, to the second edition of the Pantometria of his father, LeonardDigges , would also seem to imply that telescopes were not unknown in Eng-land previous to the seventeenth century ;—“ My father, by his continuellpainfull practices, assisted by demonstrations mathematical, was able, andsundrie times hath, by proportional glasses, duly situate in convenientangles, not only discovered things farre off, read letters, numbered piecesof money, with the very coyne and superscription thereof, cast by some ofhis freends of purpose upon downs in the open fields, but also seven milesoff declared what hath been doone in private places.” Some remarkablepassages to the same effect are to be found in Dee's preface to the editionof Euclid, published by him in 1570.

There are also two Italian philosophers who deserve to be mentionedin connection with the invention of the telescope. Battista Porta , in hisMagia Naturalis, originally published in 1561, remarks that by combiningtogether convex and concave lenses, objects may be seen enlarged. Hethen proceeds to describe an instrument capable of being constructed uponthis principle, but his language is so utterly obscure as to defy interpre-tation. Again, Antonio de Dominis, Archbishop of Spalatro, in a post-humous work entitled De Eadiis Visus Sc., which was published in1611, traces very clearly the progress of rays in passing through convexand concave lenses, and remarks that by placing one of each kind at acertain distance apart, the direct and refracted rays will not interfere witheach other. He adds that the proper distance between the two lensesmust be found by experiment, and that the effect of their adjustment willbe to magnify objects by increasing the angle under which they are seen.It is to be borne in mind, that this work was published at a time whenthe invention of the telescope was already notorious throughout Europe .Bartolo, the editor of the work, states, however, in the preface, that themanuscripts communicated to him by the author had been written twentyyears previously, and that he received full authority from him to publishthem with the addition of one or two chapters.

Notwithstanding the plausible statements contained in the variouspassages above cited, there does not exist clear proof that the specula-

* Opus Majus, Pars Portia, caput iv.,p. 357. Lond., 1733.