Please substitute the following Index in place of the one which 
appeared on p. 3 of the Index Slip to Part I. of this volume : 
the name of Mr H. Levy , one of the Authors, was then 
omitted. 
Milne, J. R., and H. Levy. — The Error caused by “Lag” in a Recording 
Instrument. 
Proc. Roy. Soc. Edin., vol. xxxiii., 1913, pp. 103-116. 
“Lag” in Recording Instruments. — The Error caused by. 
J. R. Milne and H. Levy. 
Proc. Roy. Soc. Edin., vol. xxxiii., 1913, pp. 103-116. 
Recording Instruments. — The Error caused by “Lag” in. 
J. R. Milne and H. Levy. 
Proc. Roy. Soc. Edin., vol. xxxiii., 1913, pp. 103-116. 
Levy, H. , and J. R. Milne. — Error caused by “Lag” in a Recording 
Instrument. 
Proc. Roy. Soc. Edin., vol. xxxiii., 1913, pp. 103-116. 
INDEX SLIP. 
Proc. R.S.E., Vol. XXXIII., Part II. 
Houstoun, R. A. — The Absorption of Light by Inorganic Salts. No. IX. 
(with A. H. Gray). No. X. (with Chas. Cochrane). No. XL 
Proc. Roy. Soc. Edin., vol. xxxiii., 1913, pp. 137-165. 
Gray, A. H. (with R. A. Houstoun). — The Absorption of Light by In- 
organic Salts. No. IX. : Solutions of Copper, Nickel, and Cobalt 
Salts in Alcohol and in Acetone. 
Proc. Roy. Soc. Edin., vol. xxxiii., 1913, pp. 137-146. 
Cochrane, Chas. (with R. A. Houstoun). — The Absorption of Light by 
Inorganic Salts. No. X. 
Proc. Roy. Soc. Edin., vol. xxxiii., 1913, pp. 147-155. 
Absorption of Light by Inorganic Salts : — 
No. IX. Solutions of Copper, Nickel, and Cobalt Salts in Alcohol and 
in Acetone. 
R. A. Houstoun and A. H. Gray. 
Proc. Roy. Soc. Edin., vol. xxxiii., 1913, pp. 137-146. 
No. X. 
R. A. Houstoun and Chas. Cochrane. 
Proc. Roy. Soc. Edin., vol. xxxiii., 1913, pp. 147-155. 
No. XL Conclusion. 
R. A. Houstoun. 
Proc. Roy. Soc. Edin., vol. xxxiii., 1913, pp. 156-165. 
