39 The plane figures with which we are concerned come mainly under the description of **graphs** of continuous variation.

1, 2, 3, 4 (plate) show enlargements from photo- General **graphs** by Hansky at Pulkowa (June 25, 1905); Appearance they are separated by intervals from 25 to 80 of photo- seconds, and he has succeeded in showing identity sphere.

Another useful set of **graphs** comprises those which give the relation between the expressions of a length, volume, &c., on different systems of measurement.

The second class of cases comprises equations involving two unknowns; here we have to deal with two **graphs**, and the solution of the equation is the determination of their common ordinates.

(C) Mensuration of **Graphs** Generally.

In particular, the equality or inequality of values of two functions is more readily grasped by comparison of the lengths of the ordinates of the **graphs** than by inspection of the relative positions of their bounding lines.

[[Mensuration Of **Graphs** 38.]] (A) Preliminary.

On calculation of moments of **graphs**, see W.

To illustrate the importance of the mensuration of **graphs**, suppose that we require the average value of u with regard to x.

(B) Mensuration of **Graphs** of Algebraical Functions.

10 But the **graphs** which should contain, besides the normal sitter, representations of deceased friends.

In his theory of **graphs**, or geometrical representations of algebraic functions, there are valuable suggestions which have been worked out by others.