74 
THE VOYAGE OF H.M.S. CHALLENGER. 
First use or 
1T*gt»ttkd Bulb. 
Miller -Cabelca, 
Negretti akd 
Z am bra. 
Views am to 
Temperature of 
Deep Sea asd 
Oceaw Circula- 
non. 
against pressure, and consequently it came to be generally believed that in all open seas 
the water below a certain depth maintained a uniform temperature of 39° F. right down 
to the bottom. Ross lays special emphasis on the fact mentioned by earlier observers 
that the temperature of the surface water falls rapidly as the depth of the sea diminishes ; 
he cites one instance when in a single day the temperature at the surface fell from 70° F. 
wher the depth was 400 fathoms, to 5 1 *5 where it was only 48 fathoms, 1 a fact now 
known to be of local, but not universal, occurrence, being apparently limited to 
windward shores. 
In 1843 Aimt introduced reversible outflow thermometers to ascertain the temperature 
in deep water, but, although ingenious, they were not simple enough nor sufficiently 
handy for ordinary observations. Maury about 1851 made some observations on the 
temperature of the deeper waters of the sea. 2 For this purpose he used cylinders made 
if non-conducting material, discarding the ordinary thermometer with an index, as the 
inch \ might move during the ascent, or in great depths the thermometer might be broken 
by the pressure ; neither did Maury approve of Sexton’s metallic thermometer with silver 
or platinum spiral, which was very expensive ; besides, he preferred simplicity in all 
instruments intended for this branch of research. Commander Rodgers, of the U.S.S. 
“Vim ennes,’ made a few interesting observations on deep-sea temperature in the Arctic 
Ocean in 1855. 
The first self-registering thermometer with bulb protected from pressure was made 
u.-e of by Captain Pullen in 1857, on board H.M.S. “ Cyclops.” Shortly after this time 
protected thermometers of the Six pattern (Miller-Casella), 3 and Negretti and Zambra’s 
protected inverting thermometers, were introduced and improved in various ways. These 
thermometers were employed during the “ Porcupine ” and Challenger expeditions, and 
are now universally used in deep-sea investigations with excellent results. 
Pctoii, i French naturalist, who went round the world about 1805, and made many 
t m, pera ture observations, held that the bottom of the sea was covered with eternal ice, 
consequently life was there impossible. Sir James Clark Ross, as we have said, believed 
the t mperature of the deeper water of the ocean to be 39° F., a belief shared by many 
of his successors, apparently because it was thought that this was the temperature of 
maximum density, as in fresh water, although Despretz and others had previously shown 
that tie maximum density point of sea- water and of salt solutions might be below zero 
('< ui i'jradc. Tin - view ;n to the temperature of deep water was supported by Leonardo 
da Vinci, L< nz, Arago, and Humboldt, who maintained that circulation was produced in 
t i cm in by the heated and lighter water of the equator flowing to the poles over the 
f rf. - , while the colder and denser waters of the poles sank and flowed along the bed of 
J. ( Kiw, A Voyage <»f Discovery and Research in the Southern and Antarctic Regions during the years 1839-43, 
London, 1847. 
1 >< > I/"-, Orui* of the Dolphin, W . hington 185 1 J See Thomson, Depths of the Sea, p. 289, London, 1874. 
