Teaching Optics with the centennial universal lantern

Abstract

A projection apparatus was bought in 1909 by the Physics Cabinet of the Polytechnic Academy (predecessor to the University of Porto's Faculty of Science) in order to present various physics experiments, mostly in the realm of Optics, to a large student audience. A stout and impressive mahogany and brass piece, with a voltaic arc lighting system, it was manufactured by the firm E. Leybold's Nachfolger, based in Chemnitz (Germany), already with a worldwide reputation as a supplier of teaching instruments and equipment to superior schools and universities. It was sold along with an extensive set of accessories, allowing for demonstrations in geometrical optics, spectrum analysis, interferometry, diffraction, polarization and double refraction. Two extra attachments, one for projecting microscopic objects, and the other for the projection of gypsum preparations in polarized light, added to the versatility of this lantern, appropriately dubbed of universal use. Both apparatus and accessories are presently to be found in the collection of the Museum of Science of our University. On studying them, we have come to the conclusion that many classical experiments in Optics may be displayed, without great effort and in an attractive manner. The adaptation to present day usage takes no more than the replacement of the lantern's voltaic arc by a suitable and safer light source. It so happens that a hundred-year old projection apparatus, fitted with a set of purposely designed add-ons, becomes so effective as its modern counterparts.