The interest which the exhibition of the telescope excited at Venice did not soon subside: Serturi describes it as amounting almost to phrensy. When he himself had succeeded in making one of these instruments, he ascended the tower of St. Mark, where he might use it without molestation. He was recognised, however, by a crowd in the street; and such was the eagerness of their curiosity, that they took possession of the wondrous tube, and detained the impatient philosopher for several hours, till they had successively witnessed its effects. Desirous of obtaining the same gratification for their friends, they endeavoured to learn the name of the inn at which he lodged; but Serturi fortunately overheard their inquiries, and quitted Venice early next morning, in order to avoid a second visitation of this new school of philosophers. The opticians speedily availed themselves of this new instrument. Galileo's tube,--or the double eye-glass, as it was then called, for Demisiano had not yet given it the appellation of a _telescope_,--was manufactured in great quantities, and in a very superior manner. The instruments were purchased merely as philosophical toys, and were carried by travellers into every corner of Europe. The art of grinding and polishing lenses was at this time very imperfect. Galileo, and those whom he instructed, were alone capable of making tolerable instruments. It appears, from the testimony of Gassendi and Gærtner, that, in 1634, a good telescope could not be procured in Paris, Venice, or Amsterdam; and that, even in 1637, there was not one in Holland which could show Jupiter's disc well defined. After Galileo had completed his first instrument, which magnified only _three_ times, he executed a larger and more accurate one, with a power of about eight. "At length," as he himself remarks, "sparing neither labour nor expense," he constructed an instrument so excellent, that it magnified more than thirty times. The first celestial object to which Galileo applied his telescope was the moon, which, to use his own words, appeared as near as if it had been distant only two semidiameters of the earth. He then directed it to the planets and the fixed stars, which he frequently observed with "incredible satisfaction."[8]