248 
Proceedings of the Royal Society of Edinburgh. [Sess. 
not represent a straight line. For large oscillations there was a distinct 
curvature of the graph with a certain value of a, while, for the same value 
of a, the graph for small oscillations was quite straight. Hence it was 
necessary to find a different value of a for the first part of the curve in 
order, if possible, to make that part also a straight line. It was found that 
the formula was applicable, with slightly different values of the constants, 
to the two parts of the graph (see Diagram I.). 
a. 
n. 
First experiment 
■{.! 
•253 
•266 
Second experiment . 
• { li 
•259 
•262 
The two experiments give practically identical results. 
(ii.) Attempts were next made to stretch the magnesium wire, but this 
