Check your comprehension

Check your comprehension

~ Did Galileo have a lot of publications?

~ Was Galileo the first man to look through a telescope at the stars?

Professor Van Helden’s fascinating and learned little monograph The Invention of the Telescope includes Galileo; it focuses, however, not on him but on the “certain Fleming,” whoever he was. We see the main evidence in this long detective story: 30-odd key passages from books, letters, journals and official documents, in the original Latin, English, Italian, French and Dutch, all with clear translations. The documents begin with Roger Racon, who wrote in about 1250 of “Glasses so cast, that...starres shine in what place you please.” They end with a long passage of 1655 from a book seeking “the true inventor of the telescope” and finding him in an artisan of Middelburg in Zeeland.

One reads the 1609 letter of Giovan-baptista della Porta himself, who says of the new Dutch wonder: “I have seen it, and it is a hoax, and it is taken from the ninth book of my De refractione. ” Nevertheless, the noble Girolamo Sirtori pursued the glass over ail Europe, seeking experts who could grind usable lenses. He examined and measured Galileo’s own tube and lenses at that famous dinner of the Academy of Lynxes in Rome where the word “telescope” was coined in the spring of 1611, yet he was not able to duplicate the success of the Tuscan artist.

There is a famous journal entry that cites a statement (against self interest) made by the son of Sacharias Janssen, the strongest candidate for the designation of inventor, suggesting that the father (an unsavory character, convicted counterfeiter) “made the first telescope in this country in the year 1604, after one belonging to an Italian which bore the date anno 190.” (Stillman Drake thinks the error was for 1590; since the text clearly intends a date, 1590 is hard to fault.) Another claimant is a Florentine. Raffael Gualterotti, who wrote Galileo in April 1610, asserting that he, and no Dutchman, was the inventor: “It is now twelve years since I made an instrument... for the benefit of a cavalry soldier … A feeble thing.”

~ What does the author refer to as ‘long detective story’? What is the main evidence in it?

~ When and where did the word “telescope” first appear?

How can all this be true? How can the telescope have become the cynosure of Europe in a year or two after 1608 and yet have remained unknown for a decade or more before that? Professor Van Helden, a historian at Rice University, offers a persuasive explanation. The erect-image two-lens instrument was indeed not very new. It had been found quite naturally during the 1590’s by combining the then common lenses of the spectacle makers. It was of some help to myopics, but its lower power and poor lenses made it a thing of no great virtue. The early optical experimenters, on the other hand, were hoping for wonders like the glass of Roger Bacon's dreams. There was no excitement in “a feeble thing” with magnification well under two diameters. But the concave lenses for the myopic grew better, their focal lengths shorter, the glass clearer; and one of those clever Middelburg artisans, or more than one, saw a new potential. The magnification, close to threefold, was striking.

We can see now, however, that in a way “telescopes” existed before anyone, including the men who made them, were aware of them.” The key point was the development of effective higher magnification. That began near Middelburg when the utility came clear. The rich, the curious and the military seized on the device. Galileo speedily developed the concept, pushed the workable power up to near 30 in a few months and put it to work penetratingly. Once the news got around more than one man realized he had already long possessed the same device, but with low magnification and used in a very different way. Quantity is the hero of this story, as it is of much science in the post-Galilean years.

Дата добавления: 2014-10-31