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SUMMARY OF CURRENT RESEARCHES RELATING TO 
is that he possessed plano-convex lenses and knew their magnifying 
power ; that he attributed this power to the fact that the lenses made it 
possible to see objects under a greater angle ; and that he perceived 
how useful such lenses might be for people with weak sight. There is 
no evidence, however, to show that he was actually the inventor of 
spectacles. That honour, it appears, must be divided between Alex- 
ander de Spina of Pisa, and Salvino degli Armati of Florence, for an 
old chronicle of the monastery of St. Katharina, in Pisa, ascribes it to 
the first, while an inscription discovered on a tombstone in the church 
of Maria Maggiore, in Florence, gives it to the second. The first 
authenticated notice of the use of glasses for weak sight is contained in 
a letter dated 1299, and Jordan di Rivalto, in a speech made in the 
year 1305, refers to the invention of spectacles as being then scarcely 
twenty years old. Thus the date of the invention was close at the end 
of the thirteenth century, but no precise year can be given. For the next 
three centuries no advance in the theory of optics appears to have been 
made, and it was not until the beginning of the 17th century that the 
Microscope and telescope were invented. Italy and Holland both claim 
the honour of the invention, and each of these nations brings forward 
different names. There is very little doubt that the honour belongs to 
Hans and Zacharias Jansen, father and son, glass-cutters of Middelburg. 
Evidence in support of their claim by the son and sister of Zacharias 
Jansen, and by Wilb. Borell his friend, is contained in a paper by 
Pet. Borelius on the invention of the telescope which appeared in 1655. 
According to the description given by Borell, the short-tube telescopes 
(Microscopes) made by the Jansens were about 1J ft. long. The tube, 
which was about 2 in. in diameter, was supported by three brass dolphins, 
and had a base of ebony on which the small objects to be examined 
were laid. The long telescope, or telescope proper, was not made by 
the Jansens until some time after the Microscope. A rival claimant for 
the honour of this invention is Lepreg, or Lipperstey, or Lipperheim, 
another glass-cutter of Middelburg. He certainly did construct a 
telescope, and was able to exhibit it to a stranger who came to Middel- 
burg (probably about 1608) in order to make inquiries about the new 
invention ; but whether his instrument was made independently or only in 
imitation of that of the Jansens it is impossible to say. In Italy, Galileo 
is generally accepted as the inventor of the telescope, but, as he himself 
allows, it was not until after he had heard of the Dutch invention that 
he attempted to construct an instrument for himself. To him is due the 
credit of being the first to direct the telescope to the heavens ; and with 
its aid in 1610 he made the discovery of Jupiter’s satellites. Although 
the earlier discovered, the Microscope was almost unknown beyond its 
birthplace at the time when the telescope was in all hands. Thus 
Cornelius Drebbel, who exhibited an instrument in London in 1621, 
was looked upon as the inventor, and is so described by Huyghens and 
many others. 
Similarly, in Italy, the Microscope was unknown until about 1624. 
One explanation of this may be found in the fact that the instruments 
were then very incomplete. For the long series of improvements, both 
in the optical and mechanical parts, which has led to the perfection of 
the instruments of to-day, the present century is mainly responsible. 
