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Rare Book Collection
Alcuni Opuscoli Filosofici

First edition, rare, of this posthumously pubished collection of scientific essays by Castelli, Galileo's distinguished student and colleague. The first essay, the largest in the book (pages 1-35), contains Castelli's principal contributions to optics. Castelli's optical investigations were continued in a treatise sent to Giovanni Ciampoli in 1639 and published posthumously in 1669. Included are many observations and conclusions with respect to the persistence of optical images, by which Castelli explained the perception of motion, the illusion of forked tongues in serpents, and other phenomena. In the same treatise he recommended the use of diaphragms in telescopes to impede transverse rays, anticipating Hevelius. His discussion of the camera obscura, the inversion of images on the retina, and of cataract (from which Galileo had recently lost his sight), although less novel, are not without interest. The mother major work in this collection concerns the physics of heat, written in two letter to Galileo. More celebrated is Castelli's discussion of heat in a series of letters to Galileo (1637-1638) and particularly his experiments with the absorption of radiant and transmitted heat by black and white objects. Two of these letters, in which the pursuit of experimental science is even more clearly described than in Galileo's work on bodies in water, were published in 1669.

Castelli's importance to science lay not only in his extension and dissemination of Galileo's work and methods, but also in his long and faithful service to Galileo during the two periods of crisis with the Inquisition. It was to Castelli that Galileo addressed his first discussion of religion and science, and it was on Castelli's advice in 1630 that Galileo transferred the printing of the 1632 Dialogue from Rome to Florence, a maneuver without which that important work might never have issued from the press. Castelli (1578-1643) was a Benedictine, consultant to Urban VIII on hydraulics, and professor of mathematics at the University of Rome, where he taught Evangelista Torricelli and Giovanni Alfonso Borelli.

ID: 2000-00055
Castelli, Benedetto

Creation Jan. 1, 1669 through Dec. 31, 1669


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