Christopher Clavius's Opera Mathematica

Christopher Clavius S. J. (1537 - 1612) was a German mathematician and astronomer. Renowned as a teacher and writer of textbooks, Clavius was particularly active in the reform of the Gregorian calendar. This is the title page of his collected works, Opera Mathematica, (1612), five volumes.

Christopher Clavius's Opera Mathematica

Giuseppe Alberti's Instruzioni pratiche per l’ingenero civile

Plate VII from Giuseppe Alberti’s Instruzioni pratiche per l’ingenero civile, (1774) [Practical Instructions for Civil Engineers]. Alberti (1712 - 1768) was an Italian engineer and architect. This illustration on page 298 explains the triangulation method of land measurement employing a sighting staff or surveyor’s cross. The instrument shown contains a compass for marking bearings.

Giuseppe Alberti's Instruzioni pratiche per l’ingenero civile

Peter Apianus's trigonometry and geography

Title page of Petrus Apianus’ A Geographical Introduction (1534). In this book, he reviews the theories of Vernerus [Johannes Werner (1468-1522), a Nuremburg priest and mathematician who devised a method of using lunar observations to find longitude] and explains the applications of trigonometry (i.e. sines and chords) in geography.

Peter Apianus's trigonometry and geography

Tycho Brahe's astronomical instruments

An illustration from Tycho Brahe's Astronomiae instauratae mechanica showing his great mural quadrant. This functioning quadrant was actually painted on the wall of his observatory, Uraniborg at Hven.

Tycho Brahe's astronomical instruments