Report of Magnctical Observations at Falmouth Observatory. 139 



very good agreement between his formula (1) and the observations 

 of Holman and others upon various gases. 



If the law be assumed, my observations suffice to determine the 

 values of c. They are shown in the table, and they agree well with 

 the numbers for air and oxygen calculated by Sutherland from obser- 

 vations of Obermayer. 



Eeport of Magnetical Observations at Falmouth Observatory 

 for the Year 1897. Latitude 50 9' 0" K, Longitude 

 5 4' 35" W. ; height, 167 feet above mean sea-level. 



The Declination and Horizontal Force are deduced from hourly 

 readings of the photographic curves, and so are corrected for the 

 diurnal variation. 



The results in the following tables, Nos. I, II, III, IV, are deduced 

 from the magnetograph curves, which have been standardised by 

 observations of deflection and vibration. These were made with the 

 Collimator Magnet, marked 6 6 A, and the Declinometer Magnet, marked 

 66c, in the Unifilar Magnetometer No. 66 by Elliott Brothers, of 

 London. The temperature correction (which is probably very small) has 

 not been applied. 



The Declination and Horizontal Force values given in Tables I to IV 

 are prepared in accordance with the suggestions made in the Fifth 

 Report of the Committee of the British Association on comparing and 

 reducing magnetic observations, and the time given is Greenwich 

 Mean Time, which is 20 minutes 18 seconds earlier than local time. 



The following is a list of the days during the year 1897 which were 

 selected by the Astronomer Royal as suitable for the determination of 

 the magnetic diurnal variations, and which have been employed in the 

 preparation of the magnetic tables : 



January ... 6, 9, 22, 23, 26. July 1, 9, 13, 18, 26. 



February... 2, 9, 17, 18, 20. August... 4, 5, 6, 24, 31. 



March 14, 15, 16, 18, 20. September 13, 18, 19, 26, 28. 



April 3, 11, 12, 15, 22. October 5, 9, 13, 20, 21. 



May 8, 9, 12, 16, 28. November 7, 8, 12, 23, 30. 



June 8, 9, 10, 12, 30. December 8, 13, 26, 27, 28. 



EDWARD KITTO, 



Magnetic Observer. 



