Convert from mark twain to point [Britain, US]

Unit Definition (mark twain)
The mark twain or twain is an old word for the number two, derived from the Anglo-Saxon twegen. The American author Samuel Clemens (1835-1910), who had been a riverboat pilot on the Mississippi in his youth, took his literary name from a traditional riverboat phrase "mark twain", meaning "exactly two" fathoms of water. This was the minimum depth needed for the boats to operate safely without running aground.

Unit Definition (point [Britain, US])
The unit of measure for the height of type, defined as 1/72 of an inch* or 0.3527777778 mm (*small differences occur in this unit between countries, the variables lying between 0.188 and 0.4mm)