Temperature of the Sea and the Air 119 



sea surface, t T the difference between it and the temperature 

 of the air, and T T' the difference between the readings 

 of the thermometer in air with its bulb dry and when it is 

 with sea-water. At the head of each table is given the 

 meteorological district of the ocean through which the ship 

 was passing, as "north-east trade winds," "equatorial calms," 

 and the like ; also the day of the month (1885) and the latitude 

 and longitude at noon of the day. The means at the foot 

 of each table are simply the arithmetical means of the numbers 

 ach column ; and their meaning and value are at once 

 apparent on inspecting the column. 



With the two exceptions above-named, the temperature 



of the sea was always found higher than that of the air, over 



the day, and only very seldom was it exceeded by that of the 



lie hotte of the day. Had the observations 



been carried on through the night, the contrast between the 



> prr.it un- would have been much greater. 



31 and 1 " 1'iu.iry I the conditions were somewhat 



On the former of the- the ship passed 



into the northerly monsoon, which prevails all down the 



n coast during the southern summer. Like tin similar 



monsoons in the northern hemisphere, it is caused by the 



proximity of a large mass of land, which gets intc; ated 



of the sun. On January 30 the wind 



been light -outh-ea>terlv ; during the night it fell calm, 



-e a light easterly wind sprang up, which gradually 



drew around towards the north and blew all day. \vitli 



sufficient force t< xartlv at the same rate as the ship 



(nj knotx) ; consequently, during the whole of the day 



>sphere on the deck was motionl.^. \\itl i>o\\ -iful 



,p everything, so that it was 

 "ssible to tmd any place v. could be got, coi 



.\ithout having been exposed influence 



v heated d< k and tittinL>. 1 



eratures are son ith. 



ire (( tl 



il IT found to !> usually l>. 

 he sea su The cause of I think, to be found 



