A translation of and commentary on Frans van Schooten's work on constructions using only a straightedge. Van Schooten's postulates for use of the straightedge, however, allow the copying of one line segment onto another.
The cost per hour of running a certain steamboat is proportional to the cube of its velocity in still water. At what speed should it be run to make a trip up stream against a four-mile current most economically?
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.