HYDROGRAPHY. IQI 



DISCUSSION REGARDING THE MEASURINGS. 



TEMPERATURE & SALINITY CURVES. 



On the plates IV — XIX, the depth, as the independent variable co-ordinate, is taken as abseisse, 

 i centimeter corresponding to ioo fathoms (188 metres). The depths ioo fathoms, 200, 300 etc. 

 are indicated by the nethermost horizontal line of the co-ordinate system, while the corresponding 

 depths in metres are marked at the uppermost one. The temperatures are represented as ordinates, 

 with a little blue circle, and the salinity as ordinate with a red circle; j(-) (see page 36) as ordi- 

 nate with a black circle. The temperatures are put down in blue ciphers on the horizontal lines, 

 the salinity in pro mille directly above , and s (-) directly below the appertaining horizontal lines. The 

 units of temperature, the salinity, and j(-) are represented by as long a line as it has been possible 

 to obtain, when everything should be included and the co-ordinale system be of suitable dimensions. 

 The number of the station and its position (Greenwich) is indicated at every system of co-ordinates. 



A matter of special importance at the drawing of the curves, is the position of the points. 

 That the curve cannot with strict accuracy be drawn through the points laid down, is justified by the 

 fact of errors being attached to the results, caused by uncertainty in the indication of the depth, as well 

 as by incorrectness in the determinations of the temperature & salinity. I have tried to draw as 

 simple and nice a curve as possible by application of the general rules for the graphic interpolation. 

 Temperature-curves of this kind were drawn on board for the sake of the meastirings, so that it was 

 possible to obtain one observation more than the usual ones when specially desired. If for all that 

 observations are wanted at many places for the exact determination of the course of the curve, this 

 may be accounted for by the fact of the zoological and botanical investigations already having taken 

 their beginning, so there was no occasion for any more hydrographic measurings which, as is 

 known, require a great deal of work and time. 



The sections are indicated by Roman numerals, and laid down in the chart — plate III — as 

 black lines. It can be seen from the chart that the sections on plate XX— XXVIII contain stations 

 nearly lying in straight lines; owing to this, only the latitude and longitude of the two outermost 

 stations have been put down, while the numbers of the stations are indicated for those places of 

 investigation which have got station-number. In one of the sections, plate XXVII, a station is put 

 down from the Norwegian-North-Ocean-Expedition; otherwise all the measurings are those of the 

 Ingolf-Expedition. The stations are put down in the sections with an interval, which is 3/ 2 of what it 

 is in the chart. This applies to all sections with exception of section plate XXIX, which has been 

 constructed on a smaller scale, the interval between the stations being only half of that shown in the 



