ABSTRACT
The œrst telescopes were little more than carnival toys, magnifying perhaps three times, and any inventor seriously interested in turning such glasses toward the sky was obliged to improve the device. This was done, for example, by Thomas Harriot in England when he used a 6-power telescope to observe the Moon in the summer of 1609 (Harriot, 1609). His image of the Moon is the earliest surviving record of a telescopic astronomical observation, but his instrument had too low a magniœcation to reveal the mountains or craters. That astonishing discovery was made by Galileo Galilei late in the fall of 1609. Although he had a later start than Harriot, Galileo rapidly surpassed the Englishman, who never published anything about his own discoveries.
