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Mathematical and Physical Papers. 

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Fig. 2. 



Comparing this with the author's formula (1), we notice that 

 the terms di and h^ — di^ are raised to the second power, and that 

 the sign of addition between the two main terms should be re- 

 placed by a sign of division. The latter is a mere misprint, as is 

 evident from an illustrative example worked out on the succeeding 

 page in the book. But the exponent is retained in this same ex- 

 ample, showing that it is designed to be there. The numerical 

 significance of the mistake may be shown by an example. 



Consider a beam 4 inches wide and 16 inches deep. Let there 

 be a rod 1 inch in diameter, so placed that its center is 1| inches 



