Scientific Lectures. 47 



iiing of the seyenteenth century.'* Descartes ascribes the invention 

 of the telescope to James Metius (Jacob Adriansv) of Alkmaer, in 

 Holland ; but" Hnygens, as well as Borellus, to John Lippensheira, or 

 Lippersy (Hans Zans, or Jansen), a maker of spectacles of Middle- 

 burgh. Prof. Moll, after an examination of official papers preserved 

 in the archives of the Hague, comes to the conclusion that on the 17th 

 of October, 160S, Jacob Adriansy was in possession of the art of 

 making telescopes, but from some unexplained cause concealed it ; 

 and that on the 21st of the same month Hans Zans, or Jansen, was 

 actually in possession of the invention ; but there is little reason to 

 believe that it was devised by either him or his son Zacharias, though 

 one of them invented a compound microscope about the year 1590.''f 



One of tlie earliest of the telescopes made by the Jansens was pre- 

 sented to Prince Maurice, to be used in his wars. It was in April or 

 May, 1609, that Galileo first heard of this, and the instrument was 

 then described to him as one which had the property of making dis- 

 tant ol)jects appear as though they were near. Galileo thereupon 

 devised how that might be affected, and the next day, according to 

 Delambre, was in possession of a telescope magnifying three times. 

 Galileo's second telescope magnified about eighteen, and his third 

 about thirty-three times." 



x^ow, Galileo did not make use of the telescope just in the form of 

 which we are speaking. Instead of taking the rounded glass or con- 

 vex lens in order to take hold of the rays after they had come 

 together, he takes a lens of the opposite shape and takes the rays in 

 the opposite state, just before they come together, so that whereas 

 the}^ cross in the modern telescope and produce an inverted image, in 

 the Galileo telescope they are seized upon before they cross, and give 

 an erect image. That is the case with all your opera-glasses, which 

 are all Galilean telescopes. " In so far as appears, the first telescope 

 of Lippersheim magnified about fifteen on sixteen times ; and he is 

 said to have observed with it the form of the planet Jupiter, and 

 some small stars (his satellites) which appeared to move round him 

 Be this as it may, those satellites were noticed by Galileo, who also 

 observed their eclipses. He also observed many of the varieties of 

 surface of the moon, with which we are at this day so familiar, as 

 well as the phases presented by Yenus and Mars, and the spots upon 



* Sir David Brewster pays this iu his "Optica ;" but in a curious old booli called the J?arai/a<A«ma- 

 tlca, by Halliwell, it was said that a telescope was made by Leonard Digges about 1571, and may have 

 been used for terrestrial purposes. 



+ So eays the Journal of the Royal Institute. 



