1898-99.] Soundings obtained by s.s. ‘ Britannia .’ 413 
gave a mean temperature of 36° *26 against 36 0, 57 by thermometer. 
These results are so close as to practically reconcile the two methods 
and confirm the accuracy of both. 
The alteration in this co-efficient has certainly occurred only 
within the last few years, and is probably due to changes in the 
methods employed in the manufacture. All conductivity copper 
is now electrically deposited, and owing to improved processes the 
density of the metal is appreciably higher than that of the 
laboratory specimens on which Dr Matthiessen’s observations were 
made. Increased density is accompanied by higher conductivity, 
and Matthiessen himself pointed out that under these circumstances 
an increased temperature co-efficient was to be expected.* 
II. Notes on the Deposit-Samples obtained by S.S. ‘ Britannia,’ 
by Sir John Murray, K.C.B. 
In November and December 1897, the s.s. ‘ Britannia,’ belonging 
to the Telegraph Construction and Maintenance Co., took an excel- 
lent series of soundings between Bermuda and Turk’s Islands and 
thence through the Windward Passage to Jamaica.! Through the 
kindness of Mr R. E. Peake, M.Inst.C.E., who supervised the carry- 
ing out of the work on behalf of the Direct West India Cable Co., 
we have been permitted to examine the deposits brought home, 
numbering in all 116 samples, ranging in depth from 224 to 3150 
fathoms. These samples may be arranged in zones of 500 fathoms 
as follows : — 
* See Temperature Co-efficients of ‘ Conductivity’ Copper, by Clark, Forde, 
and Taylor, London, 1899 (published privately). 
t For complete list of the soundings, see Admiralty Blue-loolc : List of 
Oceanic Depths and Serial Temperature Observations received at the 
Admiralty during the year 1897, from H.M. Surveying Ships, Indian Marine 
Survey, and British Submarine Telegraph Companies ; Hydrographic De- 
partment, Admiralty, London, February 1898, pp. 52-56. See also the 
accompanying map, on which nearly all the £ Britannia ’ soundings are laid 
down in a distinctive type, as well as all other known deep-water soundings 
in the same region. 
