This is the title page of the geometry book of Jacob Kobel (1460 - 1533). The book dealt primarily with measurement, showing its readers how to use various instruments to measure fields, determine heights of buildings, and perform various other necessary tasks.
This is from a letter of June, 1695 in which Leibniz is discussing differentiation with Johann Bernoulli. The work in which these letters appear is the Virorum Celeberr. Got. Gul. Leibnitii et Johann Bernoulli Commercium Philosophicum et Mathematica, originally published in 1740.