iv PREFACE 



every one had liis own worlc to attend to and had little or no time to spare 

 for the most hard pressed of his colleagues. As will be seen later I did receive 

 considerable help, but this could not be depended upon and the programme of 

 magnetic and meteorological work had to be planned for one man. Even then 

 it was found impossible to carry out this limited programme, for difficulties with 

 the instruments were unending and new problems connected with the effects of 

 the cold and the blizzards on the self-recording instruments cropped up almost 

 daily. Some of these had been anticipated and precautions taken, but frequently 

 experience proved them unavailing. From tlie first the whole of ni,y time was 

 taken up in keeping the record of the most important elements complete and 

 there was no opportunity for making elaborate investigations of special problems. 

 What is more, the whole conditions are so different from those with which one 

 is fam,iliar that it takes at least a year to adjust one's ideas to them. At 

 the end of the first year I could see many interesting problems calling for inves- 

 tigation and had planned to follow them up during the second year's work, 

 but this could not be done for I was recalled to my work in India, when the 

 Terra Nova returned to the Antarctic in January 1912. 



The most obvious omission in the meteorological record is that of atmos- 

 pheric humidity. There are two methods of measuring humidity : first by means 

 of wet and dry bulb thermometers and secondly by means of hair hygrometers. 

 The first however is very unsatisfactory at low temperatures and Mr. Dines in 

 reviewing the two-hourly readings of the wet and dry bulb thermometers made 

 on t»he Discovery Expedition wrote : — • 



' The general opinion of meteorologists seems to be that the tables by 

 which the relative humidity is obtained from the wet and dry bulb 

 readings are open to doubt at very low temperatures and very low 

 values of the humidity and hence it hardly seems worth while cal- 

 culating the values of the humidity from these readings.' 

 ' One cannot help feeling regret that the opportunity to revise the humidity 

 tables at low temperatures could not have been utilised.' 

 With the whole of the wet bulb readings taken on the Discovery Expedition 

 unused I did not feel inclined to add to the accumulation. Also there was much 

 more important work to be done in the Antarctic than revising the hum,idity 

 tables, for this can be done in more accessible regions of the globe. I therefore 

 decided to take no more wet bulb readings. 



The use of the hair hygrometer at low temperatures has been studied by 

 Professor Mohn and his students in Norway, and a hygrometer designed which 

 is said to be reliable in use. In the short time available for preparation before 

 the expedition sailed I had no opportunity to obtain and famiharise myself with 

 this instrument. The consequence was I removed direct observations of the 

 humidity of the atmosphere from my programme hoping that I should be able to devise 

 some indirect method of observation when in the Antarctic. The opportunity 

 for this however never arose, so humidity is not discussed in the present work. 



