463 



IX. NOTES ON OPEN AIR TEMPERATURE, SCREEN TEMPERATURE, 

 AND ON TERRESTRIAL RADIATION. 



BY 



W. H. DINES, F.R.S. 



REGULAR 2-hour observations were commenced on February 9, 1902, and were continued until 

 February 15, 1904. A few observations are missing between February and .March, 1902, and only a few 

 readings of the wet bulb were taken between May 6 and September 10, 1902. From this date until 

 November, 1903, the observations are practically complete. 



On November 9, 1903, the night observations from 10 p.m. to 6 a.m. inclusive ceased, and after the 

 middle of January, 1904, four observations only at 8 a.m., noon, 4 p.m., and 8 p.m. were taken. 



The information with regard to the thermometers is not as full as might be desired, and there are 

 some points which have required investigation. The thermometers were mercury ones, and 'on several 

 occasions the entry " Frozen " occurs. Many times the temperature given is below the freezing point of 

 mercury ; on some of these occasions the note " spirit thermometer " occurs, but temperatures of - 45 F. 

 and even lower are frequent. In some of them the wet bulb is stated to be frozen, but it is not 

 uncommon to find both wet and dry bulb thermometers agreeing well, and both below - 40 F. This 

 question has been investigated at the National Physical Laboratory at Bushy (see p. 15), and it has been 

 proved that mercury may remain unfrozen and contract at temperatures considerably below its freezing 

 point. The whole question of these temperatures and of the corrections of the thermometer has been 

 investigated by Dr. CHREE, and I have accepted the temperatures with which he has supplied me, feeling 

 quite certain, in view of his experience and knowledge of the subject, that it would be superfluous for me 

 to enter into any further investigation. 



The period spent in the Antarctic region was just two years, and the annual temperature curve in 

 fig. 1 is obtained from the daily observations. The 2-hourly observations were not maintained during 



+ 30 



+zo 



8- 









cr 



-I- 10" 



t-30 



fZO 







-10" 



-20" 



Fig. 1. 



the last three months, the officers and crew being fully occupied with the more important work of 

 extricating the ship from the ice. Two years are not enough to give a reliable curve of the monthly 

 temperatures, and we have no knowledge whether the years in question were mild, average, or severe. 



