These applications are sometimes treated under arithmetic, sometimes under algebra; but it is more convenient to regard **graphics** as a separate subject, closely allied to arithmetic, algebra, mensuration and analytical geometry.

The science of **graphics** is closely related to that of mensuration.

While mensuration is concerned with the representation of geometrical magnitudes by numbers, **graphics** is concerned with the representation of numerical quantities by geometrical figures, and particularly by lengths.

There are also cases in which **graphics** and mensuration are used jointly; a variable numerical quantity is represented by a graph, and the principles of mensuration are then applied to determine related numerical quantities.

It is important to begin the study of **graphics** with concrete cases rather than with tracing values of an algebraic function.

Graphic representation thus rests on the principle that equal numerical quantities may be represented by equal lengths, and that a quantity mA may be represented by a length mL, where A and L are the respective units; and the science of **graphics** rests on the converse property that the quantity represented by pL is pA, i.e.

C. Turner, **Graphics** applied to Arithmetic, Mensuration and Statics (1907).