Galileo, perspective and mathematical instruments

Sven Dupré

This paper deals with a little discussed aspect of Galileo’s science, that is, Galileo’s involvement with mathematical instruments from the beginning of his career. It discusses two networks, one revolving around his teachers Ostillo Ricci, and Bernardo Buontalenti, better known for his stage design, the other around his Paduan patron Gian Vincenzo Pinelli, both highly involved with either designing or collecting mathematical instruments. While Galileo’s invention of the geometric and military compass is well known, it is shown that Galileo’s involvement needs to be extended to other instruments like astrolabes and sundials. Considering that Galileo was the exponent of the mathematical culture of the Renaissance, this might hardly be surprising. However, it sheds a new light on the art and science debate that has grown around Galileo during the last decade. The projection techniques used by Galileo in his astronomy, for example the orthographic projection, were not so much the product of his acquaintance with ‘artists’ as they were a consequence of his knowledge of projection techniques incorporated in the design of mathematical instruments, for example the analemma or the projection of De Rojas. While the painter Ludovico Cigoli is often considered to be Galileo’s source of these projection techniques, it is better to consider Cigoli’s drawing instruments and projection techniques as the consequence of his acquaintance with the same tradition of mathematical instrument design, shared by ‘artists’ and ‘scientists’ alike at the turn of the 17th century.

On the history of the nocturnal

Dr Günther Oestmann

The purpose of the nocturnal is finding the time by night from observation of the fixed stars. Contrary to the common planispheric astrolabe, it is a universal instrument, i.e. it can be used in any latitude. Nocturnals were very popular time-telling devices until the 18th century and were particularly used by mariners. The paper deals with the history of this instrument and its literary tradition (manuscripts and textbooks), which has not been given much attention.

About the Ramsden Circle at the Palermo Observatory

Dr Ileana Chinnici

The famous Circle commissioned in 1787 by Giuseppe Piazzi (1746-1826) from Jesse Ramsden (1730-1800) for the newly established Palermo Observatory is the only altazimuth instrument with large circular scales ever constructed. The Circle has recently been restored and placed in its original site. In this paper we discuss the instrument compared to other large circular scale instruments made at the end of the 18th century.

The meridian circles of Pistor and Martins

Joerg Zaun

The first meridian-circle for the observatory of the Berlin Academy was set up in 1838. The instrument had been ordered in 1828 from Carl Pistor, one of the most enigmatic figures in the history of Berlin instrument making. The Berlin Academy’s meridian circle was the first that Pistor had built, and he presented his ideas and plans for the construction in a detailed report to the Academy, which gives some interesting insights into the construction process that he used. In the years 1845 to 1873, when the firm Pistor & Martins was under the leadership of Pistor’s son, Gottfried, and his son-in-law, Carl Martins, at least thirteen more meridian circles were constructed for observatories in Europe and America. It is clear that the firm was one of the most important suppliers of this type of instrument at that time. Furthermore, instruments constructed many years later still clearly show the influence of Pistor’s original design.