TEMPERATLRE OP THE SEA 23 



to FciTol they made some interesting- experiments on CUAP. I. 

 the temperature of the sea and the decrease of heat in KxperimentB 

 the successive strata of the water. The thermometer '-^^ i'enol 

 on the bank and near it was from 5-i'5^ to 55-9°, while 

 in deep water it stood at 59° or 59-5°, the air being 55°. 

 The fact that the proximity of a sand-bank is indicated 

 by a rapid descent of the temperature of the sea at its 

 surface, is of great importance for the safety of navi- 

 gators ; for, although the use of the thermometer ought 

 not to supersede that of the lead, variations of tempera- 

 ture indicative of danger may be perceived by it long 

 before the vessel reaches the shoal. A heavy swell 

 from the north-west rendered it impossible to continue 

 their experiments. It was produced by a storm at sea, 

 and obliged the English vessels to retire from the coast, 

 — a circumstance which induced our travellers speedily 

 to embark their instruments and baggage, although they 

 were prevented from sailing by a high westerly wind 

 that continued for several days. 



