Miscellanea 
99 
In this case there are only two "interpolation-lines," viz. BE nud AC, for CH is the same as 
BE and HB, BF and CG are all the same as AC with difierent starting-points ; in fact we can 
in general deal with any half quarter of the square BCEH (i.e. half of any one of the triangles 
formed by two diagonals and a side) and use the results as applicable to all cases. 
Example. If we wish to interpolate for we should take one quarter of the way between 
Mo,o and ; if a third term were required we should take cither Wio.g or «_8,4) find the latter 
would generally be preferred as it is nearer the value required. 
Difference in x =5. 
Fig. 7. 
This is a very common case and there are only two necessary " interpolation-lines." It will 
be noticed that there is sometimes more than one line that could give the interpolation, but 
I have shown the one most likely to give a good result. 
Difference in x =3. 
» y =2. 
Fig. 8. 
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