An early abridgement of Fibonacci's De practica geometrie

In this article I will show that sometime before the end of the 14th century a now lost abridgement of Fibonacci’s De practica geometrie (1220) was made, and that three closely related Italian treatises on geometry from the 14th and 15th centuries were copied from this abridgement. The contents of the three manuscripts are compared closely with those of De pratica geometrie. Rather than being a chapter-by-chapter description of the treatises, my comparison is organized under the headings Basic Definitions, Pisan Measurements, Figures to be Measured, Tools for Measuring, and Examples of Measurements.