The imposing burning devices of the German savant Ehrenfried Walther von Tschirnhaus – concave mirrors of copper sheet and convex lenses of cast glass of nearly one meter in diameter – were the most powerful solar furnaces available around 1700. Coveted at princely courts and learned academies across Europe, these devices were used by Tschirnhaus and his collaborators for the key melting experiments leading to production of what is likely the first European hard-paste porcelain – and then re-used decades after Tschirnhaus‘ death to create high temperatures in key experiments challenging the long-believed immutability of diamonds.

Several of Tschirnhaus‘ burning lenses survive, whereas others are only known through written sources. This paper presents new findings on the provenance, use, and re-use of several of these instruments. It also sketches a program to replicate and test a double-lens apparatus by Tschirnhaus.

It is not surprising that many artists were caught up in this paradigm shift. Sometimes they were conscious of their motives, inspired by genuine admiration for the emerging science. Sometimes it just happened. Some of these artists are well known while others are only mentioned in passing.
My paper will focus on Jost Ammann (1539-1591), one of the most prolific and successful German engravers of the late 16th century. His name is often associated with that of Wenzel Jamnitzer, a renowned Nuremberg jeweller, draughtsman and mathematical instrument maker with a profound interest in science. Ammann was the author of the engravings in Yamnitzer's book Perspectiva corporum regularium and the famous portrait of the Nuremberg goldsmith in his study.
Ammann's work on Leonhard Fronsperger's The Book of War (Kriegßbuch) undoubtedly drew him even closer to the world of science and scientific instruments. This can be seen both in his graphic work and in some of the instruments that are decorated with images that can be traced back to Ammann's work. His example clearly demonstrates the mutual enrichment of the world of the creators of early scientific instruments and the art world of the period, as I will try to show.

Is it possible to measure the accuracy of an astronomical data without certain relevant information such as the exact position of the observer? Would precision measurements help detect the accuracy? These questions became crucial when studying the observational data of John Greaves. He was a 17th-century English polymath who embarked on a journey to the Ottoman realm between December 1637 and April 1639. He conducted numerous astronomical observations in Istanbul, Rhodes, Alexandria, and Cairo in pursuit of his two main goals: creating a calendar and making a new world map. He employed various instruments including a quadrant, sextants, and a telescope, some of which can only be defined as state of the art. While he described pinpoint locations for his activities in Istanbul, Rhodes, and Cairo in his notebooks, he completely neglected to note any details of his observation spot in Alexandria, where he conducted longest-term and systematic observations. The observational data he obtained shows remarkable precision but their accuracy remains a question. Here we propose some possible areas in and near Alexandria where Greaves might have conducted his observations between December 1638 and April 1639 based on the 17th-century layout of Alexandria and some hints from his personal notebooks. We will then argue the precision and accuracy of some of his instruments based on the data.

Taqī al-Dīn Muḥammad ibn Maʻrūf (d. 993/1585) was a polymath who worked on optics, astronomy, mathematics, and mechanics. He had a particular interest in turning theoretical ideas into applications. In that regard, he created forty-nine optical experiments based mostly on the optical hypotheses proposed by his predecessors such as Ibn al-Haytham and Kamāl al-Dīn al-Fārisī. His goal was to verify or falsify the mathematical models using repeatable experimental setups. These forty-nine experiments can be grouped in four: (i) the propagation of light, (ii) reflection, (iii) refraction, and (iv) the light-colour relationship. In 2023, Dr Taha Yasin Arslan and I started a project to replicate Taqī al-Dīn’s experiments using tools -as similar as possible- that was available to him in the 16th century with a goal to find out whether these experiments were indeed can be actualized and to determine if one can achieve proper answers with them. The aim of this paper is to reveal how we managed to follow the footsteps of Taqī al-Dīn on a number of experiments and also to discuss the difficulties we encountered in the replication processes of such experiments.