56 



SCIENCE. 



[N. S. Vol. XVIII. No. 445. 



think Cook's voyage of less importance in 

 antarctic geography than Willces' voyage. He 

 says: "If such extraordinary reasoning were 

 to be allowed, one might say far more justly 

 of the first transatlantic voyage: 'North 

 America was not discovered, a fact which 

 would seem to rank the voyage of Columbus 

 as of much less importance than the voyage 

 of Cabot.' " But if Dr. Mill had compared 

 the voyage of Columbus with the voyages of 

 Columbus' predecessors, his simile would have 

 been exact. A number of men sailed west- 

 ward before Columbus, but their efforts pro- 

 duced no tangible result beyond showing that 

 the ocean was a big space of water. But 

 Columbus brought out the fact that there were 

 great lands in the west, and for this he justly 

 gets deserved credit. In the same way Cook 

 only found ocean and ice round the South 

 Pole, while Wilkes first discovered the exist- 

 ence of an Antarctic continent, and he, there- 

 fore, like Columbus, is entitled to the credit 

 of the discovery. 



Dr. Mill states that I have ' done a pa- 

 triotic service, and also a service to science, 

 in setting out the real achievements of 

 Charles Wilkes,' and for this I beg to thank 

 him. But he says I claim for Wilkes 'first 

 discovery.' I have never claimed that Wilkes 

 was the first to sight land in the Antarctic. 

 On the contrary, I think it may have been 

 Don Gabriel de Castiglio in 1603, or perhaps 

 some entirely forgotten mariner whose pos- 

 sible discovery of West Antarctica before 

 1569 may have been the origin of the ' Golfo 

 de S. Sebastiano' on the charts of Mercator 

 and Ortelius. What I claim for Wilkes is 

 that he was the first to discover land masses 

 which were probably continental in their di- 

 mensions, and the first to announce to the 

 world the existence of the probable South 

 Polar continent. And every Antarctic dis- 

 covery since the time of the American Ex- 

 ploring Expedition goes to show that Wilkes 

 was correct. 



Dr. Mill says that I am 'unjust to the 

 memory of Sir James Clark Eoss.' He does 

 not specify how, but he apologizes for Eoss as 

 follows: 'We feel sure that Eoss was not 



aware of Wilkes' orders dated 1838 at the 

 time he wrote of the American . and French 

 expeditions.' Yet Eoss had read Wilkes' 

 ' Narrative,' for he quotes it repeatedly. Of 

 the long and serious investigation I made of 

 Sir J. C. Eoss' charges against Wilkes — in 

 which I stated that Eoss paid no attention to 

 the statements nor to the charts published 

 by Wilkes, but quietly started a grievous 

 error, and also that none of Wilkes' discov- 

 eries were disproved by Eoss for the simple 

 reason that Eoss never was within sighting 

 distance of any part of Wilkes Land — Dr. 

 Mill does not say a word, and by his silence, 

 therefore, he assents to my conclusions. 



ED'\\aN Swift Balch. 



THE SPECIFIC HEAT OF MERCURY. 



To THE Editor of Science: May I direct 

 attention to a corollary to the recently pub- 

 lished work of Messrs. Barnes and Cook on 

 the specific heat of mercury?* In these ex- 

 periments a slender thread of mercury was 

 heated by passing a current through it, and 

 the results agree fairly well with other re- 

 sults obtained by previous experimenters who 

 heated mercury in the ordinary way. The 

 agreement might be still closer if the other 

 results were as accurate as those of Messrs. 

 Barnes and Cook. Petterson and Hedelius 

 (quoted in the article referred to) failed to 

 work accurately enough to detect the decrease 

 of the specific heat with rise of temperature, 

 and Eegnault even thought the change to be 

 in the opposite direction. As it is; the re- 

 sults agree well enough to show that, to about 

 one part in 300, the specific heat is not altered 

 hy the passage of a current. 



This fact, I think, can hardly be self-evident, 

 and is worth an experimental proof. Spe- 

 cific heat is known to vary with temperature, 

 i. e., rapidity of agitation of the molecules, 

 and experiments along this line may give us a 

 clue to the nature of conduction, whether this 

 takes place entirely through the intermeshed 

 ether, or partly by a motion (twisting or other- 

 wise) of the particles. 



That the same is true for water as for 

 mercury has been shown by the experiments 



* Physical Review, February, 1903. 



