of Edinburgh , Session 1878-79. 77 
their steam holes, Delessite, Chlorophseite, Hullite, Saponite, and 
Celadonite. 
Of these, Delessite seemed to be confined to igneous rocks of Old 
Red Sandstone age — Chlorophseite and Hullite to more recent vol- 
canics ; while the others occurred in rocks of both of these ages. 
He doubted whether the so-called Viridite of petrologists had any 
claim to a specific title — possibly it might be either Delessite, 
Saponite, or Celadonite. He regarded it as most probably the last 
of these. No attempt had been made to show that it was not an 
already named substance ; and until there was good appearance of 
this, it was in no way entitled to a place in mineral nomenclature. 
Two new minerals, belonging to the first of these groups, were 
noticed as occurring in granite near Tongue in Sutherland, and in 
Rubislaw quarry. 
3. On Deep-Sea Thermometers. By Mr J. Y. Buchanan. 
For the purpose of observing the temperature of the waters below 
the surface in lakes and seas, two classes of thermometers have been 
used — namely, ordinary thermometers and self-registering ones. 
The earliest observations were made with the ordinary thermometer, 
and it was used in one of two ways — either it was sunk itself to the 
desired depth, and was so enveloped and protected by badly con- 
ducting material, that in bringing it up again through the layers of 
water of different temperature it had not time to alter its own tem- 
perature, or a quantity of the water at the desired depth was enclosed 
in a bucket of suitable construction and brought to the surface, and 
then immediately tested with the thermometer. Many very excellent 
and trustworthy observations exist which have been made in one of 
these ways. Our first knowledge of the temperature of the deep 
water of fresh-water lakes was obtained from the observations of 
Saussure on the lakes of Switzerland, made with a thermometer so 
padded and protected that it could be drawn up through 1000 feet 
of water of any temperature likely to be found in nature without 
sensibly altering its temperature. The self-acting bucket or sea- 
gauge was used at an earlier date in the determination of the tem- 
perature of the deep water of the ocean. The accuracy of the 
results obtained by this method depends greatly on the skill of the 
observer. In the case of Saussure and of Fischer and Brunner, the 
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