Miscellanea 
97 
Graphically these examples can be shown very simply by the following figures. Using dots 
to show the jjosition of given values, then, if the required value is ?<2,6) we join (0, 0) to (2, 6) and 
produce it till it i^asses through another point {x\ y'), then we can interpolate for M2,6 between 
Fig. 3. 
In a similar way if there are three variables the following diagram may be constructed, in 
which dotted lines show those parts of the figure that would not be visible if we had a solid, and 
the dots show the positions of given values ; the " line of interpolation," as it might be called, 
is OB. 
In fig. 2 we have represented the surface by giving the heights of the ordinates at the given 
points, and the same could have been done in fig. 3, but it would have been impossible in fig. 4 
B 
Fig. 4. 
Biometrika vi 13 
