1906-7.] On the Application of a Differential Densimeter. 
229 
Graphic Representation of the Results. 
Following the method adopted in the Challenger Reports , the results 
obtained from the density measurements are set forth graphically in 
figs. 5a and 5b. 
The author would venture to express the hope that the methods 
described and the data contained in this communication may prove 
helpful to those who are interested in the various problems connected 
with oceanography. 
I desire to express my best thanks not only to Mr R. T. Gunther, who 
has given me so much valuable assistance, but also to the President and 
Fellows of Magdalen College for the continually increasing facilities 
which they offer for research work. 
I would also take this opportunity of expressing my high appreciation 
of the courtesy of Captain Plunket of the Oruba and of the Managers 
of the Orient Steam Navigation Company, who not only made the 
necessary arrangements for collecting and packing the samples of water, 
but also delivered the same in London free of charge. Without their 
willing and generous co-operation this research would, in all probability, 
not have been attempted. 
Daubeny Laboratory, 
Magdalen College, 
Oxford. 
APPENDIX. 
Relative Density Determinations with Pyknometers. 
In order to test the degree of accuracy attainable by means of the 
various types of densimeter described, the relative densities of all the 
samples of water were first measured at 18° C. in the usual manner; and 
for this purpose five Sprengel pyknometers were employed. These were 
constructed from ordinary test-tubes, and proved highly satisfactory 
on account of the rapidity with which the charged instruments assumed 
the standard temperature of the bath in which they were placed. This 
was doubtless due to the thinness of their walls and to their low capa- 
cities, the latter ranging from 15 to 19 c.c. A series of experiments showed 
that a charged pyknometer acquired the temperature of the bath so readily 
