1 90 



NA TURE 



[December i6, 1909 



■do this," they say, " but at the same time we know that 

 in actual practice a cut on a hand, which lasts for a long 

 time in a coal mine, here, when powdered by the ore, gets 

 well verv quickly." 



Chr. Antoonovich. 

 St. Petersburg, Russia, M. Possadskaya 21, 

 December 4. 



Lunar Rainbow of December i. 



On Wednesday, December i, about 11 p.m., we saw 

 here a very fine lunar rainbow. It was a perfect bow in 

 the west, showing on a black sky. At the two ends the 

 colours of the rainbow were to be seen quite plainly, 

 though there was only about half a moon. Had there been 

 a full moon, the sight would have been very fine. The 

 rainbow was visible for about twenty minutes. 



RiCHENDA Christy. 



Orchards, Broomfield, Chelmsford. 



THE TERCENTENARY OF THE TELESCOPE. 



THE year 1609 is one of the most remarkable epochs 

 in the history of astronomy. In the summer of 

 that year Kepler's book on the motion of Mars was 

 published, in which for the first time the actual orbit 

 of a planet in space was determined, while astro- 

 nomers had hitherto only been able, with more or less 

 success, to investigate the projection of that orbit on 

 the celestial sphere. In the same year the newly- 

 invented telescope was directed to the heavenly bodies, 

 and enabled mankind to form an idea of their con- 

 stitution, instead of being, as hitherto, reduced to 

 making wild guesses on this subject. But while many 

 years had to pass before Kepler's work became gener- 

 ally recognised (even Galileo never accepted it), the 

 telescope at once became an indispensable tool to 

 astronomers. 



Though many attempts have been made to prove 

 that some of the ancient or mediaeval philosophers made 

 use of telescopes, it is now generally acknowledged 

 that the telescope was not known to anyone before 

 the year 1608. i On October 2 of that year Johan 

 Lipperhey, a spectacle-maker of Middelburg, sub- 

 mitted to the States General an instrument for seeing 

 at a distance, which he had invented, "as was known 

 to the members of the States," and demanded either a 

 patent for thirty years or an annual pension. The 

 States General desired the inventor to produce a bino- 

 cular telescope, and when he did that they eventually 

 paid him goo florins for three instruments of this 

 kind, while the patent was refused on the plea that 

 the invention had already become known to many 

 people. These facts are certain enough, but it is 

 quite possible that Lipperhey may not have been the 

 first to construct telescopes, but that the claims of 

 Zacharias Janssen, another spectacle-maker of Middel- 

 burg, may be w-ell founded. It appears that this man 

 had invented a compound microscope in 1590. A storv 

 was current early in the seventeenth century that some 

 children, when playing with lenses, had found that a 

 weathercock viewed through two of them appeared 

 much enlarged and turned upside down, and that this 

 led to the invention of the telescope. But a telescope 

 which produces an inverted image must have been the 

 so-called astronomical telescope soon afterwards in- 

 vented by Kepler, which has a convex eve-lens, and 

 not the Dutch or Galilean telescope with a concave 

 eye-lens r)f which the modern opera-glass mav servp 

 as a specimen. A man who had invented a compound 

 microscope would not be unlikely to possess lenses 

 good enough to produce a fair image of a weather- 

 cock, and to have been capable of modifying this acci- 



NO. 2094, VOL. 82] 



dental discoverv by substituting a concave eye-lens to 

 make the image upright. Some person is said to have 

 gone to Middelburg to procure a telescope from the 

 spectacle-maker there, but to have applied, by a 

 mistake, to Lipperhey, who thus first heard of the 

 invention. 



Whether Lipperhey or Zacharias Janssen was the 

 first to make telescopes will probably never be settled 

 with absolute certainty, but in any case the first 

 telescopes were undoubtedly made in Middelburg. In 

 the introduction to the catalogue of his library 

 (p. .xviii), Libri describes a small tract printed at Lyons 

 and dated November 12, 1608, in which mention is 

 made of " nouvelles lunettes " made by a poor, pious 

 and God-fearing man of " Mildebourg " ; and the 

 writer states that "even the stars whicli ordinarily 

 do not appear to our view and our eyes on account 

 of their smallness and the weakness of our visior. 

 may be seen by this instrument." From several other 

 contemporary sources we know that knowledge of the 

 new invention spread very rapidly, so that telescopes 

 were not difficult to procure in the spring of 1609, both 

 in the Netherlands and elsewhere. In December, 1608, 

 the .States General sent two telescopes made by Lipper- 

 hey to King Henry IV. of France; others were 

 publicly offered for sale in Paris about the end of 

 .April, 1609, while the news of the invention hacf 

 reached Venice in December, 1608, and a specimen of 

 the new instrument was brought to Milan in the fol- 

 lowing May. The wonderful new toy was so very 

 simple that it is not strange that " there was nobod\- 

 who did not say he had invented it," as a contem- 

 porary writer tells us. .\mong these was Galileo, who- 

 in .August, 1609, on the Campanile of San Marco at 

 Venice, e.\hibited a telescope made with lenses pur- 

 chased in that city. He claimed to have merely heard 

 that a certain Belgian had presented to Prince Maurice- 

 of Nassau a glass by means of which distant objects 

 were seen as clearly as if they were quite near, and 

 that this meagre information sufficed to enable him 

 in a single night to design a telescope. If the informa- 

 tion received by Galileo was really as scanty as he 

 says, it is very strange that the man who from it 

 constructed a telescope should shortly afterwards, in 

 his " Sidereus Nuncius," show that he hardly had 

 grasped the most rudimentary notions as to the pas- 

 sage of rays of light through lenses and the formation 

 of images. He would have done better if he had 

 followed the explanation of the effect of convex and 

 concave lenses given by Kepler in his book on optics, 

 published in 7604.1 



But even if we cannot give Galileo the credit which 

 he demanded of having re-invented the telescope, and 

 though, as we have seen, others before him had 

 pointe3 a telescope to the stars, he deserves full credit 

 for having at once grasped the great possibilities 

 offered by the instrument, and for having made the 

 first serious attempt to explore the heavens with it. 

 He did not grind the lenses himself, but made use of 

 such as he could purchase. Judging by the very rough 

 sketches of the lunar surface given in his little book 

 " Sidereus Nuncius " (published in March, 1610), his 

 small telescopes, magnifying from three to thirtv 

 diameters, cannot have been very good ; still, they 

 were sufficient to show that the moon was a body like 

 our earth, having mountains and plains, that the 

 Milky Way really was composed of innumerable stars ; 

 and, above all, they enabled him to discover the four 

 satellites of Jupiter in January, 1610. Continuing his 

 work, he detected in the following autumn the phases 

 of Venus and Mars, and about the same time he 

 became greatly puzzled by the peculiar appearance of 

 Saturn, which planet, instead of showing a round 



"Ope 



, p. -56. 



