This paper investigates the ‘parallelogrammum prosopographicum’ (prosopographical parallelogram), a little-known device for drawing from life using parallel lines. The instrument, described in an article published in 1673 in the Philosophical Transactions , was adapted from Christoph Scheiner’s stereograph and designed as a practical method to bypass the visual effects of perspectival foreshortening. The present paper examines the geometrical and mechanical principles of the parallelogram and the rationale deployed by its inventor. It then locates the implications of the device within a history of orthographic projection through mathematical instruments in late seventeenth-century London. The paper ultimately argues that the programmatic aim of the parallelogram constitutes a relevant case study for a history of early modern architectural representation, a permeable field of research laying on the threshold between projectivity, mathematical practice and instrumentation.

中文翻译：

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平行四边形

本文研究了 'parallelogrammum prosopographicum'（prosopographical parallelogram），这是一种鲜为人知的使用平行线绘制生活的装置。该仪器在 1673 年发表在《哲学汇刊》上的一篇文章中有所描述，改编自 Christoph Scheiner 的立体图，并被设计为一种绕过透视缩短的视觉效果的实用方法。本论文研究了平行四边形的几何和机械原理及其发明者部署的基本原理。然后，它通过 17 世纪后期伦敦的数学仪器，在正字投影历史中定位了该设备的含义。