A Magnetic Survey of the Fortieth Parallel. 147 



Table V shows the error and rate of chronometer Frodsham 4066, 

 during the course of the journey. 



Comparative observations were made at Kew before and after the 

 survey between the unifilar employed in the regular monthly determi- 

 nations at that observatory and the Owens College instruments, with, 

 the following results : — 



Declination. 



Kew Declinometer 

 ,, 



Owens College Declinometer. . 



May 29, 1878. 

 June 7, „ 



19 13 36 W. 

 19 17 44 

 19 12 03 



Kew Declinometer 



Owens College Declinometer. 



Sept. 25, 

 „ 26, 

 Oct. 3, 



19 12 10 

 19 13 33 

 19 14 01 



The observations for the determination of the astronomical meridian 

 at the several stations are given in Table VI. 



Table VI. 







Local apparent 



© Circle 

 reading. 





Meridian 



Station. 



Date. 



time of passage 



© Bearing. 



reading of 







of centre. 





circle. 



New Haven. . 



July 18 



h. m. s. 



7 44 24 -6 a.m. 



30 06 3 7 5 



90 04 50 E. 



300 o'l 45 



La Junta . . 



„ 29 



5 40 54 -4 p.m. 



203 10 42 -5 



77 48 22 W. 



280 03 01 



Denver 



Aug. 8 



9 23 00 -2 a.m. 



37 44 22 



113 18 13 E. 



284 26 09 



Cheynne 



„ 10 



11 15 38-3 „ 



10 55 22*5 



156 11 16 „ 



214 44 16 



Salt Lake City 



„ 15 



10 33 12-8 „ 



247 00 10 



138 27 17 „ 



288 32 53 



Green River 



„ 26 



9 00 14-9 „ 



27 08 43 



115 09 23 „ 



271 59 20 



Grand Island 



„ 28 



10 11 12-0 „ 



76 13 46 



134 46 10 „ 



301 27 36 



Council Bluffs 



» 30 



7 37 12-8 „ 



45 26 56 



99 27 40 „ 



.305 59 16 



Chicago 



Sept. 2 



4 10 39 -0 p.m. 



193 11 46 



102 56 00 W. 



296 07 46 



Allegheny . . 



5 



4 28 49 -3 „ 



20 18 38 



99 58 11 „ 



120 16 49 













120 22 37* 



Washington 



I 8 









115 18 37* 



Observatory fixed marks. 



The corresponding azimuthal readings of the magnet are contained 

 in Table VIa. 



