PREFACE. 



THE present volume contains a series of Reports on various portions of the Physical observations made 

 during the voyage of the "Discovery" in the National Antarctic Expedition, together with other 

 observations taken in different regions of the world in further illustration of the subjects under discussion. 

 The Royal Society, having undertaken the supervision and publication of the Physical work of the 

 Expedition, placed the preparation of these Reports in the most competent hands available. 



The Tidal work of the "Discovery," which was in charge of Lieutenant M. BAKNK, R.N., has been here 

 discussed by Sir GEORGE DARWIN, to whom we are also indebted for the discussion of the Tidal 

 observations of the " Scotia," which were entrusted to the Royal Society by Dr. W. S. BRUCE, the leader 

 of the Scottish Antarctic Expedition. The analysis of the "Scotia" observations has l>een furnished by 

 Mr. SELBY and Mr. HUNTER, Tidal Assistants at the National Physical Laboratory. 



The other Physical work of the " Discovery " which is included in the present volume, consisting of 

 Pendulum observations, Earthquake registers, Auroral journal and Magnetic observations, was in charge 

 of Mr. L. C. BERNACCHI during the Expedition, except the Magnetic work at sea, which was undertaken 

 by Lieutenant ARMITAGE. Engineer Commander R. W. SKELTON, besides his valuable contributions to the 

 Photographic work, rendered much assistance in the Pendulum observations. All the officers of the ship, 

 both scientific and naval, lent their help in the recording of Auroral phenomena. The results of these 

 various lines of physical research are presented in the following pages. 



The account of the Pendulum observations has been prepared by Mr. BERNACCHI. The discussion of 

 these results has been supplied by Dr. CHREE, F.R.S., of the National Physical Laboratory, whose 

 valuable assistance has been placed at the service of the Royal Society by the Director, Dr. GLA/K- 

 BROOK, F.R.S. 



To Dr. JOHN MILNE, F.R.S., we are indebted for the interesting discussion of the results of the 

 Seismological observations and the comparison of these observations with others made contemporaneously 

 in different parts of the world. 



Mr. BERNACCHI has re-written and arranged the Auroral journal, to which Dr. E. A. WILSON has 

 contributed a series of striking drawings. 



The Report on the Magnetic observations has been supplied by several contributors. Mr. BKKNAI < in. 

 who spent some months in the reduction of the Differential Magnetic work, has written the introductory 

 statement as to the conditions in which the observations were taken. Commander CHETWY.ND, K.N., of 

 the Hydrographic Department of the Admiralty, has been so good as to supply the section on the 

 reduction of the Absolute and Relative Magnetic observation*. 



As planned by the Royal Society, simultaneous Magnetic observations were taken on pre-arranged term- 

 days at certain observatories, as well as at the Winter Quarters of the "Discovery." The results as 

 measured from the magnctograms have been given in Tables of Hourly Values compiled by Commander 

 CHETWYND and by Dr. CHREE. 



The rest of the Magnetic work of the " Discovery " is now in course of being worked out at the 

 National Physical Laboratory and will form the subject of a separate volume. 



The Magnetic work of the "Scotia," which was entrusted to the Royal Society by Dr. BRUCE, was placed 

 in the hands of Dr. CHREE, who has discussed it in the present volume, while Mr. MUSS.MAN, who took the 

 original observations, has furnished the account of the conditions in which they were taken. 



ARCH. GKIKIK, 



R.S. 

 Royal Society, Burlington House, 



2nd July, 1908. 



