GO 
THE VOYAGE OF H.M.S. CHALLENGER. 
• responding to the series of integer temperatures Fahrenheit. I am indebted to Mr. 
Buchanan f*>r having placed a manuscript copy of his (and Hubbard’s original) table at 
my disposal. From Buchanan’s table I calculated the volumes at t°, in terms of the 
volume at 0° C. as unity. Hubbard’s results are of importance, because, forming as they 
do part of “Maury’s Sailing Directions,” they are sure to have been hitherto, and to be 
1 • rhaps in the future, used largely by seafaring scientific men. Mr. Buchanan, in fact, 
used them for the reduction of his specific gravities during the cruise, because at that 
time there were no other tables published which he saw reason to prefer. It is perhaps 
• ■' well for me here to state at once that Hubbard, as one of the results of his work, 
a -sells that in ocean-water (not in sea- water generally) the variations in salinity are too 
small to appreciably affect the law of thermic expansion. 
{-) Ekman’s. — I never had the original memoir at hand ; what I utilised are his 
tables on the relative volumes of sea- waters as reprinted in the Norwegians’ memoir,* 
1 :| ge 53. Ekman operated on four waters, the specific gravities of which were as 
follows : — 
Water A B C 1) 
is S i6= 1016-03 1019-82 102306 1026-95 
Only the water D falls fairly within the area of my experiments. Ekman’s temperatures 
range from — 5 C. to +25° C. 
! IR cker’8. -I very much regret that up to the time when the first proofs 
this menu -ir passed through the press, I knew this most excellent research only by a some- 
■ me ign abstract in the Royal Society’s Proceedings, and, misled by some remarks in the 
Norwegians memoir, came to form an incorrect estimate of its importance. Since then, 
bow. ver, I have, through the courtesy of the authors, come into possession of a copy of 
their full memoir as pn sented to the Royal Society in November 1875, and printed in 
this Sx-icty’s Transactions, vol. clxvi. part 2, p. 405. I hardly need say that what I give 
bn'- — ju« 1 on the authority of these two experimenters is taken direct from the 
: n.'.ir quoted. I horpe and Rucker determined the relative volumes at a series of 
Matures ranging from about 0" to 30° or 40° C. of four sea-waters, the specific 
gravities of which were found to be as follows : — 
Water A BCD 
0 S 0 1033015 1028-66 1024915 1020755 
B a :rf t' r from the North Atlantic; from it the other three were prepared — A 
ij 'ration, ( and D by dilution with certain proportions of distilled water. The 
Orion of each of the f>>ur waters was determined twice by means of two different 
* Quoted in footnote, page 53. 
