Title graphic for the exhibit: From Eyeballs to Electrons page title: Glass Eyes

Lick's Great Refractor The Great Lick Refractor In 1609, Galileo Galilei in Italy and Thomas Harriot in England turned a new Dutch invention—then variously called a truncke, a tube, or a perspective glass—on the stars. In effect, a telescope gave an observer a much larger eye in the form of a lens which collected far more light, concentrating it at a focus. Even the modest increase in brightness and clarity afforded by the first small telescopes revealed a hitherto invisible universe full of unimagined wonders.

Astronomers made careful drawings at the eyepiece or used instruments to measure what they saw. As the size and light-gathering power of telescopes increased, so did the sophisitication and precision of instrumentation. By the nineteenth century, the astronomer's toolkit included micrometers for measuring positions, angles, and angular distances; photometers for gauging luminosities; and spectroscopes for analyzing starlight. As pre-telescopic observers had done before them, astronomers of the telescopic era were pushing visual observing to its limits.

Click on the thumbnails below for more on late nineteenth-century visual observing at Lick Observatory. old eyepieces Eyepieces old eyepieces Drawing of Jupiter duplex micrometer thumbnail link Duplex micrometer nebular spectrum drawing thmbnail link Spectrum drawing Pickering photometer wedge thumbnail link Photometer wedge