viii 
Contents. 
PAGE 
On Currents produced by Friction between conducting Substances, 
and on a new form of Telephone Eeceiver. By James Blyth, 
M.A., . . . . . . . .548 
Note on the Present Outbreak of Solar Spots. By Professor Piazzi 
Smyth, ........ 554 
Positive and Negative Electric Discharge between a Point and a Plate 
and between a Ball and a Plate. By Alexander Macfarlane, M.A., 
D.Sc., . . . . . . . .555 
Kesearches in Thermometry. By Edmund J. Mills, D.Sc. Com- 
municated by Professor Crum Brown, .... 562 
Preliminary Notice of a Method for the Quantitative Determination 
of Urea in the Blood. By John Haycraft, M.B., B.Sc., . . 564 
On the Phenomena of Variation and Cell-Multiplication in a Species 
of Enteroinorpha. By Patrick Geddes. Communicated by Pro- 
fessor A. Dickson, . . . . . . .571 
On the Accurate Measurements of High Pressures. By Professor Tait, 572 
Sixth Report of the Boulder Committee, Plates XVII., XVIII., XIX., 577 
On Two Masks and a Skull from Islands near New Guinea. By 
Professor Turner, . . . . . . 635 
On an Ultra-Neptunian Planet. By Professor G. Forbes, . . 636 
Remarks by the Chairman, J. H. Balfour, M.D., on delivering to 
Professor Fleeming Jenkin the Keith Prize, . . . 637 
Non-Euclidean Geometry. By Professor Chrystal, . . . 638 
Note on the Theory of the “15 Puzzle.” By Professor Tait, . 664 
On the Constitution of Adult Bone-Matrix and the Functions of 
Osteoblasts. By De Burgh Birch, M.B., Demonstrator of Phy- 
siology in the University of Edinburgh, .... 666 
On Two Unrecorded Eggs of the Great Auk ( Alca impennis) dis- 
covered in an Edinburgh Collection ; with Remarks on the former 
existence of the Bird in Newfoundland. By Robert Gray, . 668 
On a New Telephone Receiver. By Professor Chrystal, . . 682 
On the Differential Telephone, and on the Application of the Tele- 
phone generally to Electrical Measurement. By Professor 
Chrystal, . . . . . . . . 685 
On the Determination of the Specific Heat of Saline Solutions. By 
Thomas Gray, B.Sc., Demonstrator in Physics, and Instructor in 
Telegraphy, Imperial College of Engineering, Tokio, Japan. Com- 
municated by Professor Tait, ..... 689 
On a “Navigational” Sounding Machine. By J. Y. Buchanan, . 694 
On the Compressibility of Glass. By J. Y. Buchanan, . . 697 
Suggestions on the Art of Signalling. By Alexander Macfarlane, 
M.A., D.Sc., . . . . . . .698 
Note on the Wire Microphone. By R. M. Ferguson, Ph.D., . 700 
On the Peroxides of Zinc, Cadmium, Magnesium, and Aluminium. 
By J. Gibson, Ph.D., and R. M. Morison, D.Sc., . . . 706 
On the Processes in Subepiphysal Bone Growth and some points in 
Bone Resorption. By De Burgh Birch, M.B., Demonstrator of 
Physiology in the University of Edinburgh, . . .706 
