208 7 J. A. POLLOCK. 
circuits have been constructed wholly of copper wire 0°33 
cms. in diameter. From the result of an experiment 
described above, I believe both circuits may be considered 
to have been formed of the copper wire. The rectangles 
were in all cases 30 cms. wide. Three methods have been 
used in the determinations. The results by the final one 
are considered of much greater weight than those by the 
earlier methods, and the observations have therefore, been 
divided in the tables. 
Table I.—STRAIGHT WIRES. 
Length of Straight Wire. 
; Perimeter of rectangle in |_Perimeter of rectangle. 
Final Earlier tune with straight wire. | Length of straight wire. 
method methods. 
310 760 2°45 
355 860 2°42 
370 886 2°40 
400 955 2°39 
445 1050 2°33 
500 1165 2°33 
520 1200 2°31 
The relation connecting the above observations is shown 
graphically in Fig. 1. 
Open circles.—The ends of the circles were bare and 
were separated by a distance of about 15 cms., so as to 
avoid any appreciable capacity effect due to their proximity. 
A result given by Mr. Close at the end of this paper, shows 
that in separating the ends of a bare ended resonator, 152 
cms. in circumference, made of copper wire 0°33 cms. in 
diameter, practically no change is made in the period of 
vibration when the distance between them exceeds 8 cms. 
The actual length of the wire is given in the table under 
the heading “length of circular arc.”’ 
