518 Prof. R. Threlfall and Mr. J. F. Adair. On the 



By applying the above formula to the weighing in sea- water at 

 17° C. and to the weighing in pure water at 16-65° C, the first expe- 

 riment gave density of sea-water at 17° = 1*02702 density of pure 

 water at 16*65°. The density of pure water at the various tempera- 

 tures was taken from Kupffer's observations as reduced by Professor 

 W. H. Miller (Everett's 'Units and Physical Constants,' 2nd edition, 

 p. 39). The densities for temperatures intermediate to those given 

 by Everett were obtained by interpolation. 



For the measurement of the density by means of the specific 

 gravity bottle, two bottles were used, one acting as a counterpoise, 

 together with the small requisite quantity of sand and aluminium 

 foil. The other bottle being quite clean was then filled with the 

 water to be weighed, great care being taken to avoid the retention of 

 any bubble of air. The dry and wet bulb thermometer apparatus 

 was observed, together with the barometer, in order to make the 

 usual corrections for weighing in air. The results of the two measure- 

 ments made by this method agreed closely with the other four 

 measurements made by weighing glass. In order to have comparable 

 results and to get a mean, the results of the measurements made at 

 17°, 18-6°, 18-65°, 19-8°, and 21° C. respectively were reduced by 

 " Challenger Report," ' Physics and Chemistry,' vol. 1, p. 70, to the 

 temperature 15*56° C. These comparable results are given in the 

 following table. 



Weights were assigned to the observations as shown. 



By weighing glass . . 



3J • • 

 JJ * * 



JJ • • 



By sp. gr. bottle . . 

 j> • • 



Experi- 

 ment. 



Density at 

 15-56° C. 



Mean. 



Weight 

 assigned to 

 observation. 



1 



2 

 3 

 4 

 5 

 6 



1 -02623 "I 

 1 -02629203 \ 

 1-02629205 J 

 1 -02599 

 1 -02628 "I 

 1 -02603 J 



1-026271 



1 02599 

 1 '026155 



3 



4* 

 1 



Hence the probable value of the density at 15*56° C. is 1*026116 

 grams per cubic centimetre. 



The densities of the water at the various temperatures of the 

 experiments at the Bay were thence found by means of the table in 

 the " Challenger Report." 



The temperatures of the water in the Bay during the experiments 

 were — 



* The high weights assigned to this observation are because the weighings were 

 taken at midnight. 



