1874.] Temperatures of the Sea at various Depths. 463 



dependency, upon recent and better data by Dr. Carpenter, acquire, 

 from this concordance, additional force and value. The author was not at 

 all aware himself, in the earlier part of the inquiry, how much had been 

 done, and often found himself framing hypotheses which, on further 

 examination, he found had been long before anticipated by others. 



The first part of the paper consists of an " Historical Narrative," 

 which embraces an account of the character, number, and position of the 

 observations made by Ellis (1749), Cook and Forster (1772), Phipps 

 (1773), Saussure (1780), Peron (1800), Krusenstern (1803), Scoresby 

 (1810 and 1822), Kotzebue (1815), Wauchope (1816 and 1836), John 

 Boss and Sabine (1817 and 1822), Abel (1818), Franklin and Buchan 

 (1818), Parry (1819, 1821, 1827), Sabine (1822), Kotzebue and Lenz 

 (1823), Beechey (1825), D'Urville (1826), FitzKoy (1826), Blossville 

 (1827), Graah (1828), Berard (1830), Vaillant (1836), Du Petit Thouars 

 (1836), Martins and Bravais (1838), Wilkes (1839), James Boss (1839), 

 Belcher (1843 and 1848), Aime (1844), Kellett (1845), Spratt (1845- 

 1861), Dayman (1846), Armstrong (1850), Maury, Eogers, Bache (1854- 

 57), Pullen (1857), "Wiillerstorf (1857), Kiindson (1859), E. Lenz (1861), 

 Shortland (1868), Chimmo (1868). 



The second part relates to the " Method and Value of the Observations." 

 Wanting a reliable self-registering thermometer, the early observers, for 

 a considerable time, used a machine contrived by Dr. Hales to bring up 

 water, by means of a bucket with valves, from the depth at which the 

 temperature was to be taken. This was used by Ellis, Cook, Scoresby, 

 "Wauchope, and Franklin, and one of a form improved by Parrot was em- 

 ployed by Lenz. Scoresby's observations in the seas around Spitzbergen are 

 of much interest. He showed that while at the surface the temperature 

 varied from about 29 to 42, the temperature at depths of from 2000 to 

 4000 feet was generally about 34 to 36 ; and there is reason to believe 

 that, with the very slight corrections suggested by Lenz's subsequent 

 researches, most of them are correct within a fraction of a degree. 



The most remarkable readings, however, taken with this apparatus were 

 those obtained by Lenz in Kotzebue's expedition of 1823. He applied to 

 the observations a correction founded on Biot's law of the variations of 

 temperature experienced by bodies in passing through mediums of different 

 temperature, and determined the lowest temperatures hitherto noted in 

 iiitertropical seas. Thus, one sounding in mid- Atlantic, 7 21' N. lat., at a 

 depth of 3435 feet, gave a corrected reading of 35'8 F., and another at a 

 depth of 5835 feet, in mid-Pacific, 21 14' N. lat., gave 36'4 F., the surface 

 temperatures being 78*5 and 79 0< 5. His observations on the specific 

 gravity of sea-water are also valuable. 



Saussure and Peron used thermometers surrounded with non-conduct- 

 ing substances, so that they might pass through the warmer upper strata of 

 water with little change. Saussure s experiments deserve notice, inasmuch 

 as, after applying a correction, they recorded, at that early period, for 



