258 A. BOYD. 
On THE ELASTIC RADIAL DEFORMATIONS IN THE 
RIMS anp ARMS or FLYWHEHLS, AND THEIR 
MEASUREMENT BY AN OPTICAL METHOD. 
By A. BOYD, B.Sc., B.E., Stud. Inst. C E. 
[Communicated by Prof. W. H. WARREN, wh. Sc., M. Inst. C.E. | 
[Read before the Royal Society of N. S. Wales, August 5, 1903. ] 
THE investigation described in the following pages was 
undertaken with the object of supplying data for the com- 
parison of the results given by the present flywheel theories 
with the results of experiment, and for the development of 
a more exact theory. The effect of curved arms and of 
flanged joints is also investigated. Hitherto the subject 
has been dealt with only ina theoretical fashion, no definite 
measurements of the actual expansions of the rim having 
been attempted. 
One of the best known treatments of the question in 
Knglish is that given by Professor Unwin in his text-book 
on Machine Design.’ He discusses the case of a homo- 
geneous flywheel running at uniform speed, and deduces 
expressions for the shearing force, bending moment and 
tension in the rim. This was worked out in a simpler 
manner some time afterwards by Professor Lanza.’ These 
theories are discussed and applied to actual cases herein- 
after. T’'wo papers on the subject were contributed by 
Mr. J. B. Stanwood,’ in which attention was drawn to the 
stresses produced in flywheel rims by the bending of the 
rim, and a method of treating the case was pointed out, 
1 Elements of Machine Design, Part II. 
? Trans. Am. Soc. Mech. Engineers, Vol. xv1., p. 208. 
3 Trans: Am. Soc. Mech. Engrs, Vols. xv. and xv. 
