Contents. 
Vll 
PAGE 
On the Application of Graphic Methods to the Determination of the 
Efficiency of Machinery. By Professor Fleeming Jenkin, . 381 
On Professor Tait’s Problem of Arrangement. By Thomas Muir, 
M.A., . . . . . . . .382 
On Mr Muir’s Discussion of Professor Tait’s Problem of Arrange- 
ments. By Professor Cayley, ..... 388 
On Amphicheiral Forms and their Relations. By Professor Tait, . 391 
On the Toothing of Un-round Discs which are intended to roll upon 
each other. By Edward Sang, ..... 393 
On the Mineralogy of Scotland. Chapter II. By Professor Heddle, 393 
Least Roots of Equations., By J. D. Hamilton Dickson, . . 393 
On New and Little-known Fossil Fishes from the Edinburgh Dis- 
trict. No. III. By Dr R. H. Traquair. ( See Appendix), . 394 
On Ocean Circulation. By John Aitken, .... 394 
On a New Investigation of the Series for the Sine and Cosine of an 
Arc. By Edward Sang, ...... 400 
Note on the Bifilar Magnetometer. By J. A. Broun, F.R.S. Com- 
municated by Professor Tait, ..... 402 
Addition to the paper “ On the Establishment of the Elementary 
Principles of Quaternions.” By G. Plarr. Published in Yol. 
XXVII. of the Transactions of the Society. Communicated by 
Professor Tait, ....... 402 
Note on Mr Muir’s Solution of a “Problem of Arrangement.” By 
Professor Cayley, ....... 402 
Preliminary Note on a New Method of Investigating the Properties 
of Knots. By Professor Tait, ..... 403 
On the Cranial Osteology of Rhizodopsis, and on some points in the 
Structure of Rhizodus. By Dr R. H. Traquair. ( See Appendix), 403 
Notice of Recent Earthquake Shocks in Argyleshire in 1877. By 
David Stevenson, Civil Engineer, ..... 403 
Additional Remarks on Knots. By Professor Tait, . . . 405 
On the Structure and Relations of the Genus Holopus. By Sir C. 
Wyville Thomson, F.R.S., ...... 405 
On the Diurnal Oscillations of the Barometer. Part II. By 
Alexander Buchan, M.A., . . . . . .410 
On the Air Dissolved in Sea- Water. By J. Y. Buchanan, . .412 
Why the Barometer does not always indicate real Vertical Pressure : 
A continuation of the Paper laid before the Royal Society of 
Edinburgh in July 1875, in which, in addition to several other 
points, this was attempted to be shown. It is now more fully 
written out. By Robert Tennent, . . . . .412 
Laboratory Notes. By Professor Tait — 
a. On an Effect of Heat on Electro-Static Action, . .415 
b. On Dr Blair’s Scientific Aphorisms in connection with the 
Ultra-Mundane Particles of Le Sage, . . .415 
