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 
