579 
of Edinburgh, Session 1877-78. 
the low central barometer rises rapidly ; but when the supply is not 
copious and uniform all round, the barometer does not rise, because, 
though the depression fills up in the rear, there is a corresponding 
opening out in the front, and the central barometer remains low 
— thus producing the central spiral inflow which generates the 
motive force to which the progressive movement is due. 
2. On the Thermo-electric Properties of Charcoal and certain 
Alloys, with a supplementary Thermo-electric Diagram. 
By C. G. Knott, B.Sc., and J. G. MacGregor, D.Sc. Com- 
municated by Professor Tait. 
3. On the Auriferous Quartz of Wanlockhead. By Dr Lauder 
Lindsay. 
4. On the Discharge of Electricity through Turpentine. By 
A. Macfarlane, B.Sc., and Mr B. J. S. Simpson. Com- 
municated by Professor Tait. 
5. Remarks on the Phonograph. By Professor Fleeming 
Jenkin and Mr J. A. Ewing. 
Professor Pleeming Jenkin and Mr J. A. Ewing exhibited a 
phonograph which they had constructed, and also some curves 
drawn on paper representing the indentions produced in the tinfoil 
of the instrument by vowel sounds. 
The phonograph exhibited had been constructed from a description 
of the instrument invented by Mr Edison, and consisted of a barrel 
about four inches diameter and four inches long, mounted on a 
spindle on which a square-threaded screw had been cut. One 
bearing of the spindle was cylindrical, and the other was a nut in 
which the screw worked. A fly-wheel handle turned the spindle 
and barrel, which advanced during each turn by a distance equal to 
the pitch of the screw. A helical groove, about — in. in breadth, 
was cut on the surface of the barrel, having the same axial pitch 
as the screw on the spindle. 
A smooth strip of tinfoil was gummed round the barrel, and in- 
