Search Loci: Convergence:
The great trick of regarding small departures from the truth as the truth itself -- on which is founded the entire integral calculus -- is also the basis of our witty speculations, where the whole thing would often collapse if we considered the departures with philosophical rigour.
Leonhard Zubler's Nova Instrumentum Geometricum
Title page of Leonhard Zubler's Nova Instrumentum Geometricum, 1607. Zubler (d. 1611) was a Swiss goldsmith and instrument maker. He is credited with introducing the use of the plane table into modern surveying. This book demonstrates and promotes the use of his instruments in techniques of triangulation. Many of the situations depicted concern warfare. Note the two surveyors flanking the title page, proudly holding their measuring instruments.
This illustration on page 11 of Zubler’s text shows a technique of multiple sightings used for topographical survey. The double armed sighting instrument allowing for the measure of angles was developed by the author.
Page 17 of Zubler's book illustrates the use of the plane table in a multi-sighting land survey.
Page 23 of Zubler’s Instrumentum demonstrates a triangulation technique for obtaining the distance to a fortress.
Illustration on page 49 of Zubler's book demonstrates a sighting technique used to determine distance between objects below the observer’s line of sight.