Roger Bacon declared in the most distinct language, that distant objects might be brought nearer, and seen more distinctly, by means of a lens or lenses; and Bap tista Porta actually read a letter, which was illegible with his naked eye, by viewing the image of it formed in the focus of a convex glass. Nothing was therefore wanting but to increase the effect by means of an eye glass, and this might have been readily done by acci dent, by any long or short-sighted person who repeated the experiment of Baptista Porta, with a concave or a convex pair of spectacles. We have no doubt, there fore, that the telescope was known as an ezlzerinzent kng bcfore it was known as an instrument, and that many ingenious persons, without any communication with one another, had constructed the instrument in a portable and efficient form.
The celebrated Descartes has stated,at the beginning of his Dioptrics, published in 1637, that the telescope was invented about thirty years before, by James Metius, a Dutchman, and citizen of Alkmaer, who accidentally thought of looking through two lenses at a time, when he was amusing himself with mirrors and burning glasses. One of these glasses happened to be convex and the other concave, and having been casually well adjusted at the opposite ends of a tube, he was surprised to observe that distant objects seen through it were large and distinct.
Passing by, as unworthy of notice and unsupported by evidence, the story of the telescope being invented by the children of John Lipperheim, a spectacle-maker of Middleburg, in Zealand, we shall proceed to consider the claims of Zacharias Jansen, as urged by Borelli in his treatise De Vero Telescopii Inventore. In this work, which appeared at the Hague in 1655, Borelli has pub lished the affidavits of several inhabitants of the city of 11,Iidclleburg, taken before the consuls in the year 1655. The son of Zacharias Jansen declares that his father made telescopes in the year 1590, (as he had of ten been informed,) and his sister refers the invention to 1610. Another person affirms on his own knowledge, that his neighbour, Hans Lipperhey (Lapfirey or Lip fierheim) made telescopes before the year 1605, while other two witnesses aver that he made them before 1609 or 1610. Antonius de Rheita, the inventor of the binocular telescope, in his Oculus Enoch ct which appeared at Antwerp in 1643, fixes the date of Lap prey's invention in 1609, anci states that, while holding a convex glass in one hand, and a concave one in the other, Ire accidentally combined them together. The claims of the Jansens are strongly corroborated by a letter from William Boreel, envoy of the states of Hol land. This gentleman was intimately acquainted m ith Zachary Jansen, the son, had often played with him in his infancy., and was frequently in the shop of his fa ther. He recollects having often heard that the Jan sens were the in. entors of the microscope ; and when he was in England in 1619, he saw in the hands of his friend Cornelius Drebbel, the same microscope which the Jansens had given to the Archduke Albert, and which this Prince had presented to him. After giving a description of this instrument, which seems to have been a compound microscope, Boreel adds, that to wards the year 1610 Jansen contrived a telescope ; and that he had no sooner discovered the proper arrange ment of lenses for this purpose, than he inclosed them in a tube, and ran with his instrument to Prince Mau rice, who, conceiving that it would be of great use to him in his wars, desired him to keep it a secret. The invention, however, became known; and a stranger having come to Middleburg to seek the inventor, ad dressed himself to John Lapprcy, whom he mistook for Jansen, on account of the proximity of their houses.
The inquiries of the stranger led Lapprey to guess at the combination of lenses, and from this circumstance lie was reputed the inventor of the telescope. The mis take, however, as Boreel informs us, was soon discover ed ; for Adrian Metius and Drebbel having come soon after this to 'Middleburg, went directly to Zachary Jan sen, and purchased telescopes from him.
In the year 1609, when Galileo was at Venice, he re ceived intelligence of the effect of the instrument pre sented by Jansen to Prince Mautice, but had no know ledge whatever ef its cons:ruction. On the first night after his return to Padua he succeeded in solving the problem, and on the day following he constructed a teles cope. This instrument, in a better form, he six days afterwards carried to Venice, and presented it to the doge, Leonardo Donati, who, in honour of his inven tien, gave him the ducal letters, which settled him for life in his lectureship at Padua, and doubled his salary. The following is Galileo's own account of the matter, as pub lished in 'March, 1610, in his Nuncius Sidereus : " Near ten months ago, it was reported that a certain Dutch man had made a perspective, through which very dis tant objects appeared distinct as if they were near ; several experiments were reported of this wonderful effect, which some believed, and others denied. But having it confirmed to me a few days after, by a letter from the noble James Bacloverc at Paris, I applied my self to consider the reason of it, and by what means I might contrive a like instrument, which I attained to soon after by the doctrine of refraction. And first I prepared a leaden tube, in whose extremities I fitted two spectacle glasses, both of them plain on one side, and on the other side one of them spherically convex and the other concave. Then applying my eye to the con cave, I saw objects appear pretty large and pretty near me. They appeared three times nearer and nine times larger (in surface) than to the naked eye; and soon af ter I made another, which represented objects above sixty times larger ; and at last, having spared oo labour nor expense, I made an instrument so excellent as to show things almost 1000 times larger, and abmc SO times nearer to the naked eye." As the telescope invented by Jansen, and known by the name of the Galilean telescope, is suited principally fer near objects, and has a very small field of view, phi losopbers soon attempted to improve the construction. Although no other telescope but this is described in the Dioptrics of Descartes, which was published in 1637, yet Kepler, in the 86th Prop. of his Dioptrics, which appeared in 1611, had explained the theory of the tele scope, and had shown that a similar instrument might be constructed, by using one or more convex eye-glasses in place of thc concave one. As one of these combina tions, however, inverted the objects, and as Kepler does not seem to have been aware of thc advantages which they possessed from the great enlargement of the field of view, Father Scheiner was the first who put in prac tice these suggestions or Kepler; and he has given an account of the performance of his telescope in the Rosa Ursina, which was published in 1650. These instru ments received still farther improvement from Father Rheita, who introduced eye-pieces with three and four lenses, and thus completed the common refracting tele scope.