MR. J. RrX4INALD ASHWORTH: 
2r) 
PART II. 
PvRSISTTVITY, ELASTICITY, AND DENSITY, AND THE TEMPERATURE COEFFICIENTS 
OF IvESISTIYITY AND ELASTICITY. 
Page 
1. Introductory.26 
2. The relation of resistivity (p) to drawing.26 
3. The relation of the temperature coefficient of resistivity (a) to drawing.28 
4. The relation of Young’s modulus (Y) to drawing. 29 
5. The relation of the temperature coefficient of Young’s modulus (y) to drawing . . . 31 
G. The relation of density to drawing and the influence of density on Young’s modulus 
and on magnetic intensity. 33 
1. The magnetic liehaviour of repeatedly drawn steel More led to the suggestion 
that some of the other physical properties of such wire would also exhibit 
interesting changes. Besides, it was worth while to attempt to trace broadly some 
connection between one property and another, since, whilst no chemical change 
presumably takes place liy drawing, yet the physical properties might be consider¬ 
ably modified. 
The selfsame Mores Mdiicli Ymre employed in determining the change of magnetic 
properties, and which have been numbered (1) to (12), have been used in the experi¬ 
ments about to be described on resistivity, elasticity, and density, in order to remove 
any doubt which might be entertained that the material of any one of these 
specimens was not identically the same during the difterent tests for its several 
proiierties. This unquestionably added to the experimental difficulties, for a length 
or thickness suitable under one set of conditions was not so suitable under other 
conditions. Thus, in the determination of Young’s modulus, the method of flexure 
had to lie employed which, under other circumstances, tvould not have been adopted. 
As the methods used here for the determination of resistivity, elasticity, and 
density are those commonly employed, it vdll be unnecessary to describe at length 
the course of the experiments, and the present part will be confined to a brief recital 
of results. 
Resistivity. 
2. The resistivity of the wires was' observed by comparing the difference ol 
potential at the ends of a knoum resistance with the difference of jiotential between 
turn points along the wire vdien the same current was flowing through the wire and 
the known resistance. Each vure has been tested liy -two, and in some cases Iw 
three, indeiiendent experiments, in which as much variation was introduced as th^ 
