1889-90.] 
Meetings of the Society. 
417 
Monday , 7th July 1890. 
Sir William Thomson, President, in the Chair. 
PRIZES. 
The Gunning Victoria Jubilee Prize for 1887-90 was presented to 
Professor Tait, for his work in connection with the “Challenger” 
Expedition, and his other Researches in Physical Science. 
The President, on presenting the Prize, said : — 
This work was primarily undertaken by Professor Tait, for the 
purpose of correcting thermometric observations affected in a com- 
plex manner by the severe and varying pressures to which the 
instruments were subjected, and deducing the true temperatures of 
the water at the great depths explored in the “Challenger” expedi- 
tion. Even had the investigation been confined to this object alone, 
it must have included highly interesting researches regarding the 
thermoelastic qualities of water, mercury, and glass. But a mere 
knowledge of the temperature at all depths in the seas and oceans 
has comparatively little interest or importance in science without 
knowledge of physical properties of sea water, such as compressi- 
bility and thermal expansivity at pressures corresponding to all the 
depths. Particularly the temperature of maximum density for any 
given pressure, which is a property calculable from the other two, is 
of supreme importance in explaining the observed results of thermo- 
metric determinations in water over submarine slopes and under the 
levels of the lips of submarine basins, and using the results for the 
theory of the great oceanic circulations. Accordingly, Tait has 
included all these subjects in his investigation, which, carried on 
with exemplarily determined perseverance, and with peculiar skill 
and inventiveness, through six years, has added to science a valu- 
able body of results regarding the compressibility and expansivity 
of fresh water and sea water at different temperatures and pressures, 
the compressibilities of water with different proportions of common 
salt in solution, and the compressibilities of glass. 
Many of us, who have seen something of the work from time to 
time, will remember with vivid interest the great Woolwich and the 
small Edinburgh guns, and the wonderful appliances for producing 
and measuring the enormous pressures up to 457 atmospheres (3 
tons weight per square inch) which were used, and their effects on 
the apparent bulk of mercury in glass. But I am afraid I have 
misused the word apparent : we saw neither mercury nor glass, but 
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