Roland Schewe and John Davis
This article offers the first comprehensive study of a newly discovered type of medieval sundial made of ivory which might well be the precursor of the well-known diptych dial form made from ivory and wood. These sundials are unique for the combination with a wax writing tablet (tabula cerata) on the reverse side, such as has been deployed as a reusable and portable writing surface in Antiquity and throughout the Middle Ages. Three previously unpublished examples of this type of sundial have been located in Germany, Italy and England. This article gives a detailed analysis of the sundials and the underlying construction principles, including considerations from the history of science, chronology and cultural history in order to answer the questions of where, when and by whom these sundials were made.
This article argues that in the early modern period, epistemic genres were transformed to suit new purposes. Modelled on the experimental essay form used by proponents of the New Sciences, the Dutch polymath and painter Simon Eikelenberg (1663-1738) wrote down ervarenissen to document how painting materials such as varnishes were prepared. Recipes have been identified as the ubiquitous vehicles for written know-how in the early modern period, yet authors continuously searched for new ways to unpack the ineffable dimensions of know-how in text. This article explores the ervarenissen as an alternative communicative strategy. Eikelenberg appropriated the experimental essay to create expressive instructions. He emphasized the specificity and idiosyncrasy of an act of making, tried to establish a sympathetic relationship with his readers, and showed how vulnerability, failure and improvisation belong to the workshop.