LXXXI. On the colours of mixed plates—Part II
The London Edinburgh and Dublin Philosophical Magazine and Journal of Science
on and the products izyzSy, I~zxSx, and I~xySxSy are plotted against the dry densities. It will be noted that the points involving ttxy lie sensibly on a straight line, whilst those involving i~yz and r lie approximately on two parallel sh-aight lines. Relations similar to the above have been obtained for each of three values of Young's Modulus and six values of Poisson's Ratio for spruce, which the writer hopes shortly to publish, and these were found to agree with the symmetrical ratios of a
... trical ratios of a body having three planes of elastic symmetry *. It may be noted th~at the number of annual rings per inch is not involved in any of the relations. The writer wishes to thank the late Principal, J. C. M Garnett, M.A., for providing facilities for conducting the research, and also Professor G. Stoney, F.R.S., for many helpful suggestions. He is further much indebted to Mr. A. L. McAulay, B.Sc.Tas., for valuable assistance with the experiments. LXXXI. On the Colours of Mixed Plates.--Part II. By C. V. RA~IAbr, M.A., _Palit .Profes.~or of .Pl~ysics, and BHABO2,T&TH BA~EttJI, M.Sc., Assistant Professor of _Physics, University el Calcutta t. 1. Inadequacy of the ~lemen~ary Diffraction Theory.