606 



INTRODUCTION. 



The following account of the physical work done in the Arctic 

 regions by past Expeditions must be regarded as a collection of 

 rough hew7i facts , which have been hurriedly brought together at 

 the request of the Arctic Committee of the Royal Society in about 

 six weeks during the months of March and April. In consequence 

 of the short time given for collating and arranging, it will, no 

 doubt, be found that many of these facts have not fallen into their 

 proper places, so as to present a clear and complete account of the 

 state of our knowledge on each separate branch of the subject, 

 and that some important results are altogether wanting ; nor has 

 it been possible, for the same reason, to discuss the observations or 

 to form them into one harmonious whole, so as to show their rela- 

 tions to one another. 



As most of the temperatures are given in Fahrenheit degrees, 

 the observations made by German observers, which are expressed 

 in degrees Reaumur, have been converted into degrees Fahren- 

 heit ; had time permitted, it would probably have been better to 

 have converted all the observations of temperature into degi'ees 

 Centigrade, especially as the observations on board the " Chal- 

 lenger " are so expressed. In some cases, especially in the accounts 

 of the earlier voyages, where the physical observations of all 

 kinds are not numerous, and are scattered throughout the narrative, 

 it has been impossible to classify them under their several headings ; 

 but the general arrangement of this, the .second part of the "Manual," 

 is according to subjects, and in each subject as far as possible a 

 comparison has been made of the observations and conclusions 

 arrived at by the several observers, and other important matters 

 added bearing on the subject. 



My thanks are due to R. H. Scott, Esq., F.R.S., for his kind 

 interest in the work and for the loan of valuable papers ; and I 

 have also to thank numerous Authors, Publishers, and Societies for 

 permission, of which I have freely availed myself, to make use of 

 valuable papers, relating to Arctic scientific work ; these arc 

 specially referred to in the " Manual." 



If the curves of temperature of the air and of the surface of the 

 sea be laid down graphically on the same sheet, there will generally 

 be seen to be a remarkable correspondence between them, and their 

 irregularities may readily be compared. It would be convenient to 

 have sheets of regularly ruled papers (similar to Letts' divisional 

 papers, with ten divisions to the inch) arranged with two or more 

 separate divisions, one for the barometric curves, 07ie for the tem- 

 perature of the air in hlackink, and for the temperature of the sea- 

 surface in red ink ; another might be added for the dry and wet 

 bulbs, or Regnault's hygrometer and the hair hygrometer, to be 

 distinguished in the same manner. It would be also of great ser- 

 vice if the changes in the barometric and thermometric curves were 

 laid down graphically on a sheet in such a way as to show their 



