November 9i »^99] 



NA TURE 



35 



I 



Hensen, Herwig, Hjort, Hoek, Knudsen, Kriimmel, Lehm 

 kuhl, Lundberg, Murray, Nansen, Petersen, Pettersson, D'Arcy 

 Thompson, Trybom, Akernian — were as follows : — 



Considering that a rational exploitation of the sea should rest 

 as far as possible on scientific inquiry, and considering that 

 international co-operation is the best way of arriving at satis- 

 factory results in this direction, especially if in the execution of 

 the investigations it be kept constantly in view that their primary 

 object is to promote and improve the fisheries through inter- 

 national agreements, this International Conference resolves to 

 recommend to the States concerned the following scheme of 

 investigations, which should be carried out for a period of at 

 least five years. 



Programme for the hydrographical and biological wot kin 

 the Northern parts of the Atlantic Ocean, the North 

 Sea, the Baltic and adjoining Seas. 



A. — The Hydrographical Work. 



I. The hydrographical researches shall have for their object : 

 the distinction of the different water-strata, according to their 

 geographical distribution, their depths, their temperature, 

 salinity, gas-contents, .plankton and currents, in order to find 

 the fundamental principles, not only for the determination of the 

 external conditions of the useful marine animals, but also for 

 weather-forecasts for extended periods in the interests of 

 agriculture. 



II. As the hydrographical conditions are subject to seasonal 

 changes, and as these strongly influence the distribution and 

 life-conditions of useful marine animals and the state of the 

 weather and other general meteorological conditions, it is 

 desirable that the observations should be made so far as possible 

 simultaneously in the four typical months, February, May, 

 August and November, at definite points along the same 

 determined lines. 



III. The observations referred to in II. would consist of: — 



(a) Obsepvations of temperature, humidity and pressure of 

 the air every two hours ; self-registering instruments for inter- 

 polation, and Assmann's aspirator should be used. 



Opportunities should be afforded to the meteorological offices 

 to make on board the ships physical observations on the higher 

 levels of the atmosphere by means of kites. 



The other meteorological observations are to be carried out 

 according to the methods adopted by the meteorological offices 

 of the nations represented. 



The observations, meteorological as well as hydrographical, 

 made on board the special steamers at the time of the survey in 

 the typical months, are to be immediately worked out under the 

 supervision of the central bureau (see C) for publication in a 

 bulletin, wherein the conditions of the sea and the atmosphere 

 are to be represented by tables and synoptical charts in co- 

 operation with the meteorological institutes of the nations 

 represented. 



(b) The temperature of the surface water shall be taken every 

 two hours, or, when necessary, more frequently. It is desirable 

 that self-registering apparatus should be used for interpolation. 



Observations on the vertical distribution of the temperature 

 are to be taken at the points mentioned in II., and should be 

 taken regularly at intervals of o, 5, ID, 15, 20, 30, 40, 50, 75, 

 100, 150, 200, 250, 300, 400 metres, and so on ; but all critical 

 parts of the curve must be determined by extra-readings. 



The bottom temperature is to be investigated with all possible 

 care. 



(c) At every point and from every depth where the temper- 

 ature is observed, a sample of water shall be collected for the 

 determination of its salinity and density. 



By salinity is to be understood the total weight in grammes of 

 the solid matter dissolved in lOOO grammes of water. 



By density h to be understood the weight in grammes^ of 

 one cubic centimetre of water of the temperature in situ t°, 

 i.e. the specific gravity in ntu referred to pure water of 



+ 4°C. (=.sQ. 



For orientation, preliminary determination of the salinity 

 should be made on board ship with expedient instruments, but 

 the exact determination of the salinity and density of all samples 

 shall take place in a laboratory for scientific work. 



(d) At certain depths of the points mentioned in II., and 



1 Units of weight are here used instead of mass-units. 



NO. 1567, VOL. 61] 



elsewhere on the surface, water samples should be collected for 

 analysis of the gas-constituents (oxygen, nitrogen and carbonic 

 acid). 



IV. For measurement of "depth the tmit to be adopted is the 

 metre, together with which the depth may be also recorded in 

 English fathoms. 



Geographical points are to be referred to the longitude of 

 Greenwich, and horizontal distances are to be expresswl in sea- 

 miles (=1852 metres). 



Thermometers to be used for the determination of the surface- 

 temperature may be either centigrade or Fahrenheit, but for 

 publication all numbers are to be reduced to centigrade. 



In the centigrade thermometers the distance between two 

 degree-marks should be at least 5 mm. and the degree divided 

 at least in two parts ; the Fahrenheit thermometer to be divided 

 in a corresponding manner. 



The use of Pettersson's insulated water-bottle is recommended 

 for moderate depths, and the thermometers used for this appar- 

 atus should have a space at least 10 mm. between the marks of 

 one degree, and the degree should be divided in ten parts. 



For greater depths of the ocean Negretti-Zambra's or other 

 thermometers of a similar type should be used. 



The glass to be used for the thermometers as well as the 

 thermometers should be tested and approved by the central 

 bureau (see C, a). 



For the determination of salinity and density either chemical 

 or physical methods may be adopted, provided that the salinity 

 can be determined with an accuracy of 0,05 in a thousand parts 

 (and the density up to 0,00004)- 



The determination of these constants can be founded either 

 upon chemical analysis of the halogen by weighing or titration, 

 or upon physical determination of the specific gravity by means 

 of hydrostalical balance pycnometers and hydrometers, provided 

 that measures be taken to exclude disturbances arising from 

 thermal effects, capillarity, viscosity, &c. 



The chemical analysis shall be controlled by physical methods, 

 and the physical determinations by chemical analysis in the 

 following manner : — 



From every collection of samples examined at least three shall 

 be selected and sent to the central bureau. Standard samples 

 shall be sent in return.^ 



The specific gravity is to be represented in the tables by the 



formula S 



(?)• 



V. Samples for gas analysis are to be collected each time in a 

 pair of sterilised vacuum tubes. 



It is desirable that the existing tables of absorption of nitrogen 

 and oxygen should be revised. 



VI. Qualitative plankton-observations should be made every 

 six hours by pumping through a silk net (N : r 18) for the space 

 of fifteen minutes, and at the same time a sample of water 

 (III. c) should be taken. 



At the points mentioned in II. samples for quantitative 

 analysis are to be collected according to the method of Prof. 

 Hensen at different depths depending on the hydrographical 

 circumstances. 



Petersen's modification of Hensen's net is recommended. 



Observations on transparency and colour of the water should 

 be made at the points mentioned in II. 



Opportunities should be afforded to bacteriological institutions 

 to carry out investigations in the ocean. 



VII. Observations on currents and tides should be carried 

 out as frequently as the circumstances allow. 



The currents should be examined, when possible, by direct 

 current-meters and by surface and intermediate floats and by 

 bottom-rollers. 



The ship should be anchored occasionally in order to make^ 

 frequent observations during a complete period of tide. 



VIII. It is desirable that a chart should be prepared of the 

 bottom of the seas examined, showing the nature of the sea- 

 bottom. 



The description of the deposits is to be carried out on a 

 definite plan, to be afterwards settled (see Appendix III.). 



IX. The normal observations are to be carried out along the 



1 By stamiard water shall be understood samples of filtered sea-water, 

 the physical and chemical properties of which are known with all possible 

 accuracy by analysis, and statements of which are sent to the difierent 

 laboratories, together with samples. 



In respect to halogen the ordinary water-samples have to be compared 

 with the standard water bjr analytical methods. 



