Hooke is said to have proposed the use of Telescopes having a length of
upwards of 10,000 feet (or nearly two miles), in order to see animals
in the moon! an extravagant expectation which Auzout considered it
necessary to refute. The Capuchin monk Schyrle von Rheita, who was well
versed in optics, had already spoken of the speedy practicability of
constructing telescopes that should magnify 4000 times, by means of
which the lunar mountains might be accurately laid down.
Optical instruments of such enormous focal lengths remind us of the
Arabian contrivances of measurement: quadrants with a radius of about
190 feet, upon whose graduated limb the image of the sun was received
as in the gnomon, through a small round aperture. Such a quadrant was
erected at Samarcand, probably constructed after the model of the older
sextants of Alchokandi, which were about sixty feet in height.