1. X-Rays and Crystal Structure, p. 31.
2. More recent determinations of this value have shown that the figure 0.000612 is too high. The value varies somewhat with the nature of the crystal face, and a better maen value is.00055.
3. [See Darwin, this Vol. p. 172 eq. (1). Ed.]
4. P. Debije, Ann. d. Phys. (4) 43 (1914) 49 [this Vol. p. 162].
5. W. H. Bragg, Phil. Mag. loc. cit. p. 891 [this Vol. p. 160].