This paper tries to analyse the figure of the mathematician, physicist, and
inventor José Ruiz-Castizo y Ariza (1857–1929), Professor of Rational Mechanics at
the University of Zaragoza and Professor of Exact Sciences at the Central University
of Madrid. Throughout a life dedicated to science, he carried out numerous jobs
in his role as a teacher and researcher. Many of them, including his “Treatise on
Rational Mechanics”, were published in monographs and scientific journals of the
time. However, the main objective of this article is to present José Ruíz-Castizo not
only through his academic activity but also as an inventor of scientific instruments.
For this, we will focus on one of his main inventions, specifically the “Tangential
evaluation Cartesian planimeter” designed by him from other existing planimeters.
From this instrument designed to measure the area of any plane figure, rectilinear,
curvilinear or mixtilinear, as well as other applications derived from the previous
one, he patented and materialised a new proposal based on his previous work on the
theory of curves.
