TEMPERATURES, SPECIFIC GRAVITIES, AND SALINITIES OF CERTAIN SEAS. 77 



The column w gives the actual additional weights, and the mean of these numbers 

 (which is also incorporated in this column) gives the mean added weight. On addition 

 of this mean number to the weight of the hydrometer in vacuo we obtain the total 

 effective weight (W + w). 



Column R gives the readings of the stem of the hydrometer corresponding to each 

 successive addition of weight, and the mean of these readings is also incorporated in 

 this column and represents the mean portion of stem immersed. 



Column V gives (l) the volume of the body of the hydrometer at 0° C. up to the 

 lowest division of the stem, the figures 18 being omitted; (2) the expansion of the 

 body of the hydrometer due to. the particular temperature of the sample during 

 experiment ; (3) the volume of the mean portion of the stem immersed, (l) is of 

 course a constant number, while (2) and (3) have been obtained by the use of the 

 formula stated above. 



The sum of (l), (2), and (3) which is given in the column expresses the total 

 volume in c.c. of the immersed portion of hydrometer, and consequently of the 

 displaced sea-water. 



Column 4 S t '. The numbers in this column represent the density of the sample 

 at the temperature of experiment (t'), and are obtained by dividing the total effective 

 weight of the hydrometer by the sum of the numbers in column V, which expresses 

 the volume of the immersed part of the hydrometer. 



Column 4S1556 gives the density of the sample at 15°'56 C. The numbers in 

 this column are calculated from those in column St- by the use of the tables con- 

 tained in Dittmar's " Report on Researches into the Composition of Ocean Water," 

 p. 70. # 



Column 4 S t gives the density of the sample at (t), which is the temperature in 0°C. 

 of the sea at the time the sample was collected. It thus gives the actual density 

 of the water in situ. The numbers in this column are derived from those in column 

 ' iSi5- 5 (i by means of the tables in Dittmar's Report in the case of those in which 

 the value of t is above 0° C. In those cases in which the value is below 0° C. 

 recourse was had to Knudsen's Tables published as No. 11 of the "Publications de 

 Circonstance " of the Conseil Permanent International pour l'Exploration de la Mer. 



N.B. — In the tables numbers which are not actually observed quantities, but which 

 have been obtained by calculation, are printed in italics. Thus in columns (t) and (T') 

 the temperatures were actually observed in ° F., and their equivalents in ° C. are printed 

 in italics. Also the figures in the last three columns are all in italics. 



* Phys. Ghem. " Chal." Exp., pt. i, 1884. 



[Observations. 



