SUMMARY OF RESULTS. 
65 
Throughout the period now under consideration, many accurate observations were Observations on 
made in all latitudes on the temperature of the surface waters of the ocean, and about 
the middle of the eighteenth century the subject of deep-sea temperature first began to 
attract attention. 1 Count Marsilli was one of the first to test the temperature of the sea 
at various depths. He made his experiments between Cassis and Riou in the Mediter- 
ranean. The table giving all his experiments shows that they were made in depths 
ranging from 10 to 20 fathoms. 2 His experiments extended only from January to June ; 
he was unable to continue them during the other months. He concludes that, were the 
experiments continued and found to concur with his own, they would prove the temper- 
ature of the sea to be the same in all seasons. Marsilli’s observations were made with 
the assistance of a common thermometer. The only merit of his observations is to show 
that scientific men were actively engaged investigating this question in the eighteenth 
century. According to Thoulet, 3 Aristotle affirmed that the surface waters were warmer 
than the deeper ones, an opinion supported by Buffon in 1750, from the fact that a lead 
drawn up rapidly from deep water communicated a marked sensation of cold to the hand. 
In 1749 Captain Ellis, during a voyage to the north-west coast of Africa, made two 
experiments at depths of 3900 and 5346 feet (650 and 891 fathoms), in latitude 25° J.3' N., 4 
with an instrument devised by Dr Hales, and described by him in a paper read before the 
Royal Society. 5 It consisted of a bucket about the size of a household pail, with valves 
at top and bottom, which remained open as the apparatus descended, and closed when 
drawn up. He obtained in both cases, with the thermometer enclosed in this vessel, 
readings of 53°, and rightly attributed this uniformity to the greater depth of water 
through which the instrument had to be hauled causing a rise in the temperature. 
Similar devices to ascertain the temperature of deep water were made use of by Foster, 
Cook, and Lord Mulgrave . 6 
Varenius, in his Universal Geography, examines the origin of the salt taste of the Opinions as to 
ocean waters, which he attributes to the presence of the particles of salt it contains ; he g^ T THE ^ EA 1? 
then inquires into the origin of that salt. Rejecting the opinions current in his time, Varenius 
he offers two hypotheses : first, the saline particles being co-eternal with the ocean, 
that question cannot be treated without reference to the origin of the ocean itself, and 
second, the fact that water carries along with it in solution the saline matters 
contained in the earth. He admits that the waters grow salter on approaching 
the equator, and less so on nearing the poles. Among the various theories which he 
brings forward to explain these phenomena are the following: — The difference of 
1 See Prestwick : On Submarine Temperatures, Phil. Trans., vol. clxv. p. 590, 1875. 
2 Marsilli, op. cit., pi. vi. p. 16. 
3 Thoulet, Oceanographie (Statique), Paris, 1890, p. 281. 
4 Phil. Trans., vol. xlvii. p. 214, 1752. 6 Ibid., p. 213. V- 
« In the “Race-horse,” 1773, between Norway and Spitzbergen. 
(summary op results chall. exp. — 1894.) 
9 
