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III. HOURLY VALUES OF DECLINATION, HORIZONTAL FORCE AND 



VERTICAL FORCE 



On Term Days during 1902-1903, in connection with the National Antarctic Expedition, 1902-1904, 



comprising Results at the following Observatories : 



GREENWICH, KEW, FALMOUTH, POIA, BOMBAY and MAURITIUS, and also at the 

 " DISCOVERY'S " WINTER QUARTERS. 



THE Royal Society arranged for simultaneous magnetic observations to be made at certain observatories on 

 pre-arranged term days during the National Antarctic Expedition, 1902-1904, simultaneous observations 

 being also made at the " Discovery's " Winter Quarters. The term days arranged for were the 1st and 

 15th of each month, each term day commencing at Oh., G.M.T., and ending at midnight. 



The resulting data received, viz., the hourly values of the Declination, Horizontal Force, and, in some 

 cases, of the Vertical Force, as measured from the magnetograms of the day, have been tabulated and 

 compiled by Commander L. W. P. CHETWYND, R.N. The values derived from the " Discovery's " 

 magnetograms have been measured and tabulated by the Staff of the Observatory Department of the 

 National Physical Laboratory, under superintendence of Dr. C. CHREE, F.R.S. 



The Observatories from which results have been received are as follows : * 



Greenwich Declination. Horizontal Force. Vertical Force. 



Kew 



Falmouth 



Pola 



Bombay 



Mauritius 



" Discovery's " Winter Quarters ... 



The maximum and minimum hourly values on each day are printed in heavy type ; where such maximum 

 or minimum was recorded at more than one hour on each day, all such maximum and minimum values are 

 so printed. 



In the tabulated values for Mauritius Observatory the data in brackets have been obtained by 

 interpolation, and where one hourly value is lacking the mean, and where necessary the range, is marked 

 with the letter " a " (denoting approximate). 



In the tabulated values for the "Discovery's" Winter Quarters, on several days one hourly value was 

 lost, the hour coming when the sheets were changed ; on other occasions a good many hours' data are 

 lacking, owing to no sheet being on the drum, or through the trace being too faint. When only one hour 

 was lacking a mean has been calculated, to which the letter " a " is attached (to signify approximate). 

 When several hours were lacking no mean is given. When the trace was off the sheet the value answering 

 to the edge of the sheet is given with the sign > or < before it, according as the trace was off in the one 

 direction or in the other. 



When the trace was off the sheet for only one hour a mean is formed with > or < in front. When the 

 trace was off for several hours no mean or range is given, except in cases where the general drift of the 

 curve justified confidence that the maximum and minimum were both included. 



* As these pages were going to press, the magnetic returns from Christehurch, New Zealand, were received. These hare 

 been tabulated by Dr. CIIEEE and will be found on pp. 177, 178, 179. 



