America's oldest scientific equipment goes on display tomorrow in Mallinckrodt lobby.

Considered the best collection of 18th century apparatus in the United States, the display includes 45 pieces and will remain for a year. University scientists assembled it after digging for ten years through laboratory boneyards.

The exhibit includes telescopes, air-pumps, balances, and three fish pickled in 1790. Many of the instruments, like Ben Franklin's electricity-makers, figured prominently in the history of science.

A man-sized planetarium occupies the center of the room. Built for the College during the Revolution, it can show the five inner planets rotating and revolving around the sun, and the various moons revolving around the planets.

Another heirloom is a chemical slide rule, built to compute mixture proportions. Chemistry was young in the 1700's and no one was quite sure what things were made of. So the slide rule gives two answers for everything, depending on what theory you believed in.

Set to find the elements in table salt, for example, the rule gives one answer presuming salt is sodium and chlorine, and another on the hypothesis that it is sodium, chlorine, and oxygen.