HYDROGR. SECTION — APPENDIX C ( 48 ) 
in Nancy for analogous investigation. Mr. Hezzanp- Hansen has undertaken to 
procure sample No.4 and he will also be able to hand over various samples taken 
earlier by the Belgica Expedition. Mr. E. W. L. Horr has undertaken to collect sample 
No. 9 and Dr. Ricaarp of Monaco has promised his valuable help in obtaining 
. samples 10, 11 and 12 and expressed the wish that a sample — No. 13 — of the 
surface-water be taken in the Mediterranean at Monaco. The last four samples 
will be taken in double quantity in order to be used like the two Skager Rak 
samples for the investigations at Monaco and of Prof. Tuouxer. 
Mr. Hezranp-Hansen and Prof. D’Arcy W. Tuompson have been communi- 
cated with im regard to the collecting respectively of the samples No.5 and 6. 
(Sign) KRÜMMEL 
NANSEN 
PETTERSSON 
KNUDSEN 
Appendix D 
A brief statement 
of the present state and of some of the most important results 
of the Hydrographical Investigations, prepared by the Hydrographical Section 
of the Council, at Amsterdam, March 1906 
Methods of Investigation 
An exact knowledge of the physical and chemical constants of the sea- 
water must be considered as an essential condition of successful hydrographical 
investigations. International cooperation has given us exact determinations of the 
relations between salinity, density, amount of chlorine, and freezing point, as well 
as of the thermal expansion of sea-water, so that the hydrographical tables now 
rest on a reliable base. Some constants, which have not hitherto been determined, 
as for instance the coefficients for the absorption of nitrogen, oxygen and carbonic 
acid, as well as for compressibility and for the relations between the amount of 
chlorine and sulphuric acid and the density, are now being worked out, and by 
help of the Central Laboratory and other hydrographical laboratories this task will 
probably be brought to completion before July 1907. | 
