EFFECTIVENESS OF THE COMMITTEE ON OCEANOGRAPHY 15 



The meteorological and hydrographies! observations made on board the 

 special steamers in the course of the surveillance during the typical months, 

 shall be immediately recorded under the control of the central bureau (see C) 

 for publication in a bulletin where the maritime and atmospheric conditions 

 shall be given in tables and synoptic tables in cooperation with the meteoro- 

 logical institutions of the nations represented. 



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

 hours and, if necessary, even more frequently. It would be desirable to have 

 automatic registering apparatus employed for the interpolation recording. 



The observations of the vertical distribution of the temperature shall be made 

 at the points mentioned in Article II and shall be made at regular intervals of 

 0, 5, 10, 15, 20, 30, 40, 50, 75, 100, 150, 200, 250, 300, 400 metres and so on; 

 however, all critical parts of the curve shall be established by supplementary 

 studies. 



The temperature at the bottom shall be determined with all possible care. 



(c) At each point and each depth where the temperature is observed, a sample 

 of water shall be taken in order to establish its salinity and density. 



By salinit}'- is meant the total weight in grams of a solid substance dissolved in 

 1000 grams of water. 



By density is meant the weight in grams 1 of 1 cubic centimeter of water with 

 a temperature of t° in situ, that is to day, the specific gravity in situ with reference 



to pure water of +4° C. (=S j^Y 



In order to determine this [salinity and density], it must be added, a preliminary 

 determination of the salinity must be made on board with suitable instruments, 

 although the exact determination of the salinity and density of all samples must 

 be made in a scientific laboratory. 



(d) At certain depths at the points mentioned in Article II, as well as elsewhere 

 on the surface, samples of water for an analysis of their gas constituents (oxygen, 

 nitrogen and carbonic acid) shall be collected. 



For the measurement of depth, the unit employed shall be the metre, however, 

 at the same time the depth may also be given in fathoms. 



The geographical points shall be in reference to Greenwich longitude [east or 

 west], and the horizontal distances shall be expressed in miles (1852 metres). 



The thermometers used in determining the temperature of the surface shall be 

 in centigrades or Fahrenheit, however, for publication all numbers shall be re- 

 duced to centigrades. 



On the centigrade thermometers, the distance between the lines of the degrees 

 shall be at least 5 mm and the degree shall be divided into at least two parts; 

 the Fahrenheit thermometer shall be divided in a corresponding manner. 



For moderate depths the use of Pettersson isolated waterbottles is recommended 

 and the thermometers used for this apparatus shall have a space of at least 10 mm 

 between the lines of one degree and the degree shall be divided into 10 parts. 



For the greatest ocean depths Negretti-Zambra thermometers or others of the 

 same type shall be used. 



The glass in these thermometers and the thermometers themselves shall be 

 checked and approved by the central bureau (See C(a)). 



For the determination of salinity and density, physical or chemical methods 

 may be used provided the salinity can be determined with an accuracy of 0.05 

 in one thousand (and the density up to 0.00004). 



The determination of these conditions may be based either on a chemical 

 analysis of the halogen by gravimetry or volumetry or by a physical determination 

 of the specific gravity by means of pyenometers of hydrostatic and hydrometric 

 balance provided the measures are taken excluding the agitation produced by 

 thermal effects, capillarity, viscosity, etc. 



The chemical analysis shall be checked by physical methods, and the physical 

 determinations by a chemical analysis in the following way: 



At least three samples of each collection examined shall be chosen and sent to 

 the central bureau. Standard samples will be returned in exchange. 2 



1 Units of weights instead of units of quantity should be used here. 



2 By standard water is meant samples of filtered sea water whose physical and chemical qualities are known 

 as ac3urately as possible through analysis; and a report of which shall be sent to the various laboratories 

 at the same rime as the samples. With regard to the halogen, the samples of ordinnary water shall be 

 compared with the standard water by means of analytic methods. 



