CONTENTS. 
PAGE 
Election of Office-Bearers, 1878-79, . . . . .1 
Opening Address. Session 1878-79. By the President, Professor 
Kelland, ........ 2 
On the Action of Light on the Iris. By William Ackroyd, F.I.C., 
&c. Communicated by Professor M ‘Kendrick, . . .37 
On a New Variety of Ocular Spectrum. By John Aitken, . . 40 
On the Principles of the Logical Algebra ; with Applications. 
Part I. By Alexander Macfarlane, M.A., D.Sc., . . .44 
Note on Ulodendron and Halonia. By D’Arcy Wentworth 
Thompson. Communicated by Sir Wyville Thomson, . . 44 
Notes on some Experiments with the Telephone. By James Blyth, 
M.A., 45 
On the Measurement of Beknottedness. By Professor Tait, . 48 
Preliminary Note on the Measurement of the Thomson Effect by 
the aid of Currents from the Gramme Machine. By Professor 
Tait, . . . . . . . . 49 
On the Disruptive Discharge of Electricity. By Alexander Mac- 
farlane, D.Sc., and P. M. Playfair, M.A., . . . .50 
Laboratory Note. By Professor Tait, . . . .52 
On the Action of Heat on the Salts of Trimethyl-sulphine. No. III. 
By Professor Crum Brown and J. Adrian Blaikie, B.Sc., . . 53 
Experimental Determination of the Electromotive Force of the 
Gramme Magneto-Electric Machine at different Speeds. By Pro- 
fessor Tait, . . . . . . . .55 
On the Law of Cooling of Bars. By Professor Tait, . . .55 
Note of the Distribution of Temperature under the Ice in Linlithgow 
Loch. By J. Y. Buchanan, M.A., . . . . .56 
On the Principles of the Logical Algebra ; with Applications. 
Part II. By Alexander Macfarlane, M.A., D.Sc., . . .61 
Remarks by the Vice-President, David Milne Home, LL.D., on de- 
livering to Professor Heddle the Keith Prize, . . .62 
Chapters on the Mineralogy of Scotland. By Professor Heddle. 
Chapter V., . ...... 64 
