CRUISES OF THE "MICHAEL SARS 



6i 



a uniform temperature throughout the deep layer also intro- 

 duces materials, particularly nitrogenous matter from the 

 surface — that is to say, indirectly from the coasts — which 

 are favourable to the development of plant life. The plants 

 were in consequence extraordinarily abundant. At Station 3 

 we found great quantities of diatoms, even in a haul with the 

 closing net from 160 metres up to 100 metres. 



On our way southwards from Station 7 we were prevented 

 by the high sea from attempting any fishery experiments, so 

 we had to content ourselves with making hydrographical 



observations (at Stations 8 and 

 9), and it was not till we were 

 well down in the Bay of Biscay 

 at Station 10 that the sea be- 

 came calmer and the weather 

 moderated. We sounded here 

 and got 4700 metres, so that 

 we now had an opportunity of 

 trying our appliances in really 

 deep water (see Fig. 40). 



We commenced at this Vertical hauls. 

 station, while the ship was still 

 hove to, by taking a series of 

 twelve water- samples as far 

 down as 4500 metres, and 

 made a number of vertical 

 hauls with the closing nets 

 down to 1000 metres. Every- 

 thing was found to work 

 splendidly, and all these opera- 

 tions took only about three 

 hours. 



Temperatures were recorded by means of the best kinds 

 of reversible thermometers, which give readings exact to 

 within a few hundredths of a degree even at the greatest 

 depths. At this station we found the temperature at 3000 Temperatures 

 metres to be 2.40° C. and at 4500 metres 2.56^ C. It was thus ^n deep water. 

 apparently warmer near the bottom than 1700 metres (or 

 nearly 1000 fathoms) above the bottom. It has often been 

 thought that the water might derive a certain amount of heat 

 from the sea-bottom, and this may have been the case here, 

 but there is also another possibility, namely, that the water 

 at 4500 metres had sunk from the upper layers and had been 



Fig. 40. 



-The Captain sounding in 4700 



Metres. 



