54 



THE VOYAGE OF H.M.S. CHALLENGER. 



" Be this, however, as it may, the following table shows the nature of the agreement 

 between the results of my original experiments [ante, p. 52] and the data derived 

 from the present investigations. The gauge and the compression apparatus were the 

 same as in my experiments of last year ; the galvanometer, the thermo-electric 

 junctions, and the observers were all different. The column MSO gives the whole 

 heating or cooling effect at 15 0, 5 C, calculated for different pressures from the results 

 of the investigation by Professor Marshall and his coadjutors. The column T contains 

 the results of my direct experiments at that temperature : — 



2) (tons) MSO T Thomson. 



1 0-131 C. 0-139 C. 0-177 C. 



2 0-294 0-311 0-355 



3 0-465 0-516 0-533 



4 0-665 0-750 0-711 



" It will be noticed that there is, again, a fair agreement ; though the results are, as 

 a rule, lower than those calculated from Thomson's formula. My own agree most 

 nearly with Thomson's formula, probably because they were very rapidly conducted. 

 As they stand, they give about 3° C. for the effect of 1 ton on the maximum-density 

 point. It is to be observed that if we could get the requisite corrections for conduc- 

 tion and for compression of mercury, their introduction would increase (as in fact is 

 necessary) the constant A above, but would have comparatively little effect on the 

 value of B, which is the quantity really sought." 



The experiments on other substances were carried out for me by Messrs. Creelman 

 and Crocket, from whose important paper 1 I extract the following results, which have 

 some connection with the subjects of this and of my former Report : — 



"Challenger" Vulcanite, at 16° C. 

 Pressure. Rise per ton. Fall per ton. 



1 



2 

 3 



1 



2 

 3 



1 

 2 

 3 



1 



2 

 3 



1 

 2 

 3 



0°-33 

 0°-31 



0°-28 



Indiarubber, at 15' 

 0°-74 

 0°-70 

 0°-70 



Beeswax, at 15° 

 0°-83 

 0°-79 

 0°-78 



C. 



0°-33 

 0°-33 

 0°-32 



0°-79 

 0°-79 

 0°-80 



0°-83 

 0°-86 

 0°-89 



Marine Glue, at 15°-5 C. 



0°-91 0°-98 



0°-85 0°-90 



0°-82 0°-91 



Sulphuric Ether, at 21° C, 



r-8 i°-9 



r-74 r-8 



r-7 r-7 



1 Proc. Boy. Soc. Edin., vol. xiii. p. 311, 1885. 



