Nipher—Graphical Algebra. 197 
Figure 4 shows clearly the nature of the changes from 
the conditions in Fig. 1. When the sides of the two 
squares lying along the horizontal axis were increased to 
y X yand x X # as in Fig. 2, the Rar a of Fig. 1 was 
ti 
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Fig. 4. 
made longer and became y X y in length, but its width 
remained unchanged. It was still y — 2. The rectangle b 
of Fig. 1 was replaced by two rectangles whose lengths 
were still w but in one of these rectangles, the width had 
increased from y—a to y>— yx —y (y—*#) and in the 
other rectangle the width had increased from y— to 
&(y—ax) = xy — 2°. 
When the next change was made, from Fig. 2 to Fig. 4 
the two rectangles to the right of x X #* in Fig. 2 did 
not change in width but their length increased from x to 
