DISCOVERIES IX THE CELESTIAL SPACES. 319 



telescopii inventore (1655). If the claim of priority be de- 

 termined by the periods at which oilers were made to the 

 General States, the honor belongs to Hans Lippershey ; for, on 

 the 2d of October, 1606, he offered to the government threo 

 instruments " by which one might see objects at a distance." 

 The offer of Metius was made on the 17th of October of the 

 same year ; but he expressly says ;i that he has already, for 

 two years, constructed similar instruments, through industry 

 and thought." Zacharias Jansen (who, like Lippershey, was 

 a spectacle maker at Middleburg) invented, in conjunction 

 with his father Hans Jansen, toward the end of the sixteenth 

 century, and probably after 1590, the compound microscope, 

 the eye-piece of which is a concave lens ; but, as we learn 

 from the embassador Boreel, it was not until 1610 that he 

 discovered the telescope, which he and his friends directed to 

 distant terrestrial, but not toward celestial objects. The in- 

 fluence which has been exercised by the microscope in giving 

 us a more profound knowledge of the conformation and move- 

 ment of the separate parts of all organic bodies, and by the 

 telescope in suddenly opening to us the regions of space, has 

 been so immeasurably great, that it seems requisite to enter 

 somewhat circumstantially into the history of these discov 

 eries. 



When, in May, 1609, the news of the discovery made in 

 Holland of telescopic vision reached Venice, Galileo, who was 

 accidentally there, conjectured at once what must be the es- 

 sential points in the construction of a telescope, and imme- 

 diately completed one for himself at Padua.* This instrument 



* The above-named physician and mathematician of the Margravate 

 of Ansbach. Simon Marius, after receiving a description of the action 

 of a Dutch telescope, is likewise believed to have constructed one him- 

 self as early as the year 1608. On Galileo's earliest observation of the 

 mountainous regions iu the moon, to which I have referred in the text, 

 compare Nelli. Vita di Galilei, vol. i., p. 200-206 ; Galilei, Opere, 1744, 

 t. ii.. p. 60, 403. and Letlera al Pfdre Cristoforo Grienberger, in mate- 

 ria delle Monltiositu del/a Luna, p.' 409-424. Galileo found in the moon 

 some circular districts, surrounded on all sides by mountains similar to 

 the form of Bohemia. " Euudem facit aspectum Luuae locus quidam, 

 ac faceret in terris regio consimilis Boemios, si montibus altissimis, inqpe 

 peripberiam perfect! circuli dispositis occluderetur undique" (t. ii., p. 

 8). The measurements of the mountains were made by the method 

 of the tangents of the solar ray. Galileo, as Helvetius did still later, 

 measured the distance of the summit of the mountains from the bound- 

 ary of the illuminated portion, at the moment when the mountain sum- 

 mit was rirst struck by the solar ray. I find no observation of the 

 lengths of the shadows of the mountains. He found the summits " in- 

 circa miglia quattro" in height, and " much higher than the mountains 



