HYDROGRAPHY. -- 



TABLES. 



All the observations concerning the surface waters are noted in the table, see page 40. From 

 this will be seen that, measuring of temperature and salinity has been made every fourth hour 

 and at all the stations. At many places every second hour, sometimes even every quarter of an hour. 

 The hour is indicated according to mean-time on board ship. The geographical longitude is reckoned 

 from the meridian of Greenwich. The appellations used for the weather, are: 



o: clear F: fog 



1: lightly clouded R: rain 



2: half clouded S: snow 



3: clouded H: hail 



4: grey, overcast M: thick with rain 

 Hz: misty 



The force of the wind is indicated after Beauforts scale (o — 12), with the addition that 3 b means stiff 

 breeze [so that the gallant sails can just be carried). The height of barometer was read on an aner- 

 oid barometer. The temperature of the air was found by means of a thermometer, supplied with a 

 scale of paper divided into whole degrees. Any high degree of confidence could hardly be reposed 

 in this thermometer. All the indications are according to Celsius scale of temperature. As to the 

 determination of the temperature, amount of chlorine, and salinity of the water, reference is made to 

 the foregoing. 



In the table of measurings made at stations, is noted the depth from which the water 

 sample is fetched, indicated in Danish fathoms & metres. The number representing the depth, is 

 underlined when the sample is taken from the bottom. As to the temperature of the water, the cor- 

 rected value is put down. At Ekman's researches (Kgl. Svenska Vetenskaps Akademiens handlingar 

 ny foljd, Bd. 9, forra del) is noted, according to Professor Wachcr bar tits calculation, how water of 

 different salinity expands by heating. From this can be deduced the specific gravity of sea-water of 

 the temperature t° when the salinity is S", or the amount of chlorine CI. 



This specific gravity is called j(j), and means the gravity of sea-water with the temperature 

 t° in proportion to distilled water at 4 . The quantity j(-), I have calculated and represented graphi- 

 cally, specially because the variation of this quantity with the depth, frequently will give a good 

 idea of the exactness with which temperature and salinity has been determined. Still is to be obser- 

 ved, that s{~^ is not the specific gravity of the sea-water in situ, as to obtain this, the pressure 

 must be taken into consideration , that is to way , s (-) must be multiplied by 1 + nix, where x means 

 the depth, and m a positive number, dependent on the temperature, pressure and salinity of the water 

 at the place concerned. Provided this calculation be made, we shall obtain — if we use a scale like 

 the one applied at the graphic representation of s (-) — a very bold curve , for which there would 

 not be room on the paper, and a smaller scale for the ordinates would entirely efface the peculiarities 

 found. And as, morover, the curves that are drawn for .r(-) give a good illustration of the manner 

 in which the specific gravity is varying with the depth, I considered it right to calculate and repres- 



