1898-1'J02. No. 4.] SEA-OBSERVATIONS. 355 



Sling-thermometers Fuess No. 1194 and No. 1195 with whirling 

 mechanism. They were destroyed on the way to Greenland in July, 1898. 

 They had been verified at the Physikalisch-Technische Reichsanstalt in 

 Charlottenburg and had no appreciable corrections at the temperatures 

 observed. 



Thermometers Ktichler Nos. 1, 3, 4, 6, 10, 12, 18 and 21. They 

 were divided into fifths of a degree centigrade, and were swung by a 

 whirhng mechanism when used for taking the temperature of the air or 

 as a psychrometer. The corrections found in Kristiania in 1898, and 

 apphed, were 



at 

 No. 3 and No. 12 were used only for Ihe sea temperature. 



The force of vapour and the relative humidity have been compu- 

 ted from the readings of the dry and wet thermometers by means of 

 Jelinek's Psychrometer- Tables. Readings of the wet thermometer 

 below zero are corrected by Ekholm's rule. 



The direction of the wind, as felt on board, was observed by the 

 mariner's compass. 



The velocity of the wind, as felt on board, was observed with 

 Mohn's hand-anemometer. Coefficient of friction one metre per second. 



The observed direction and velocity of the wind have been con- 

 verted into the true astronomic direction and true velocity in metres 

 per second, by taking into account the deviation of the compass, the 

 variation of the compass or magnetic decimation, the lee-way of the 

 ship, the rate and course of the ship, and the observed direction and 

 velocity of the wind. 



The direction of swell or sea was observed by compass and reduced 

 to true direction. 



The state of sea was estimated in accordance with the usual scale, 



= dead calm 4 = moderate 7 = high 



1 = very smooth 5 = rather rough 8 = very high 



2 = smooth 6 = rough 9 = tremendous. 



3 = slight 



The hours of observation are ship's local time, civil date. 

 The position of the ship. The latitude and longitude (Greenwich 

 Mer.) for each hour of observation have been computed from the data 



