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SCIENCE PROGRESS 



say upwards towards us from the plane of the paper, producing 

 three more forms, thus from the first square : 



Example of Secondary Derivativeg. 



and similarly for the other three squares. 



We have now a total of sixteen squares with each of the 

 numbers i, 2, 3, etc., occupying the left-hand top cell in turn. 



Again, we can read each of these sixteen squares in four 

 ways, according to which corner we allot to the left-hand 

 top cell. Thus the primary square may be read as : 



