Giovanni Poleni and his Experimental Philosophy Theatre
Dr Sofia Talas
The Venetian Marquis Giovanni Poleni became in 1739 the first professor of Experimental Physics in the University of Padua, and he inaugurated in 1740 his ‘Teatro di Filosofia Sperimentale’, the first university physics lecture room in Italy.
Until his death, in 1761, Poleni went on enriching his Theatre, buying his instruments abroad or having them made by local craftsmen. At the end of his life, Poleni had collected almost four hundred pieces, one hundred of which still exist. These instruments are now part of the collection of the Museum of the History of Physics at Padua University.
In this paper, we will examine Giovanni Poleni’s scientific activities in Padua and in Venice, and his collection of instruments will be presented and described.
Two symbols of power
Dr Catarina Isabel Carvalho
The Chinese Magnet is one of the most astonishing and curious pieces of the Physics Museum of the University of Coimbra. This Museum has its origins in the Experimental Physics Cabinet which belonged to the Faculty of Philosophy created during the Educational Reform made by the Prime Minister of King José I, the Marquis de Pombal, in 1772.
The legend says that the stone was offered by the Chinese Emperor to King D. João V. When it got to Portugal the lodestone was mounted in an original and unusual structure, surrounded by a royal crown of gilded metal.
William Dugood, Fellow of the Royal Society, also mounted another one with a quite similar structure known as ‘The Countess of Westmorland loadstone’, now in the collection of the Museum of History of Science of Oxford. This man of science, went to Portugal where he made observations about the magnetic properties of the stone that resulted in his Dissertação Sobre os Maravilhosos Effeitos do Magnete ou Pedra de Cevar (‘Dissertation on the Effects of the Loadstone’).
Both of these stones are scientific instruments and prove to us that science was one of the main interests of royalty and aristocracy. But they are also symbols of social status and political power.
On two unpublished letters by Boscovich regarding his work on optics, and on the finding of a vitrometre
Dr Carlo Triarico
Boscovich’s research in the field of optics, with which he was trying to improve astronomical observation, took up all his life. His plan to create a suitable optics theory emerged, as a matter of fact, alongside his research concerning the construction and use of instruments in which various observational errors, not least the one due to chromatic aberration, could be overcome. Among the many types of instruments he designed to overcome this problem, the vitrometre stands out; an instrument which was long in use and proved to be a vital tool for examining the quality of glass.
As is well known, although we have some evidence of Boscovich’s work in this field, we nevertheless still lack the elements which would enable us to outline a systematic history of his research. Two letters that Boscovich wrote towards the end of his life, and which had remained unknown, have only just emerged from the Archives of the Ximenian Observatory in Florence. These contain the description of some ideas relevant to research on the nature of light, observation instruments and achromatic lenses. Also mentioned is the water telescope, an instrument which the Dalmatian scientist used for his experiments in the second to last decade of the 18th century. Thanks to these two unpublished letters one can glean the way Boscovich conducted research, and the means he used. These two letters were sent to Leonardo Ximenes when he was working in his astronomical observatory in Florence, and date from the first months of 1786. They contain the description of instruments and plans devised by Boscovich, including his attempt to win the competition for making flint glass, which had been announced by the French Academy for the second time.
My paper will also report on the discovery of a Boscovich vitrometre from amongst the Ximenian Observatory’s old instruments. The vitrometre in question is of the type constructed by Lorenzo Selva, an optician who worked together with Boscovich and who created an achromatic telescope for this Ximenian Observatory. The vitrometre is 250 mm long and is made of brass; it takes the form of a compass with two outstretched legs whose spread is regulated by a screw, and it carries two stands on which lenses under examination can be placed. A graduated arch has a 60o main scale. The instrument is incomplete. No evidence of its purchase was found in the Archives, but it can safely be assumed that it came into Ximene’s possession after 1775, the year in which he made an instrument inventory.