OCEANOGRAPHICAL RESULTS, MICHAEL SARS, 1900. 141 



to salinity have not yet been definitedly determined, we cannot 

 expect to find absolute agi-eement between Helland-Hansens deter- 

 minations by titration and ours witli the hydrometer of total 

 immersion; but if his titrations have been made shortly after 

 the samples were taken it is nevertheless remarkable how good 

 agreement there is upon the whole ; the mean difference between 

 the two series of numerous determinations is 0"035 *^/oo, which Hel- 

 land-Hansen's determinations are lower than ours^. 



The determinations with the hydrometers of total immersion 

 are naturally the most accurate, of the two methods; and they 

 therefore form an excellent control of the results of the titrations. 



As a general rule it may be said that wherever, the titra- 

 tions seemed to indicate sudden and irregular changes in the 

 salinities at various depths of a series of water-samples, the 

 more accurate determinations with the hydrometer of total immer- 

 sion almost always proved that these apparent irregular changes 

 were due to accidental errors. Our investigations demon- 

 strate on the whole that the changes in the salinities and densi- 

 ties of the water at various depths of the Norwegian Sea are 

 extremely gradual and regular. 



PI. 3 gives the curves of three series of Helland-Hansen's 

 determinations by Titration (the dotted lines) at Stats, 7, 8, and 

 46 as compared with the curves of the determinations with the 

 hydrometer of total immersion of water-samples from the same 

 depths at the same stations. Helland-Hansen's determinations 

 were made in the end of August and the curves prove that his 

 determinations of the water-samples from Stat. 46, collected short 

 time before, agree extremely well with our determinations with 

 the hydrometer, while his determinations of water-samples from 

 Stats. 7 and 8 collected a month before, do not agree as well, 

 and demonstrate even great irregularities, which are evidently due 



^ In tlie Sections, Pis. 6 — 11, I have therefore increased his determinations 

 of the Salinity by D'Oi^/oa, in order to make them comparable with ours. 



