642 Prof. Pollock: Comparison of Periods of 
respective lengths of the two circuits when the electrical 
oscillations connected with them are in unison, are placed in 
the same row, the fundamental mode of vibration only being 
investigated. The rectangles have been made with sides of 
thin brass wire 0°04 cm. in diameter, the ends being of 
copper wire 0°33 cm. thick. The other circuits have been 
constructed wholly of copper wire 0°33 cm. 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 resuits 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 | Perimeter of rectangle. 
| in-tune with straight. |>__— (9 .gaeee 
Final Beekes | ee | Length of straight wire. 
method. methods. 
310 | 760 | 245 
B55 860 | 2°42 
370 | 886 | 2-40 
400 | 953 | 2°39 
Nal | 1050 : 2-33 
| 500. | 1165 | 2°33 
poo | 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 Close at the end of this paper, shows that in 
separating the ends of a bare-ended resonator, 152 ems. in 
circumference, made of copper wire 0°33 cm. 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 are.” 
iM 
