316 



Royal Society : — 



Table Il.=-Showing the comparison of the Ratios of the larger Dis- 

 turbances of the Declination at the different hours of local solar 

 time at Kevv and Hobarton. 



Local 



Kew. 



Hobarton. 



Kew. 



Hobarton. 



Local 



astronomi- 



Westerly 



Easterly 



Easterly 



Westerly 



civil 



cal hours. 



deflection. 



deflection. 



deflection. 



deflection. 



hours. 



18 



1-85 



1-18 



0-37 



042 



G A.M. 



19 



1-83 



1-75 



038 



0-44 



7 A.M. 



20 



1-48 



1-76 



036 



0-62 



8 A.M. 



21 



1-23 



1-47 



0-38 



0-60 



9 A.M. 



22 



1-2G 



1-38 



0-33 



0-54 



10 A.M. 



23 



1-21 



1-31 



0-39 



053 



11 A.M. 







1-38 



1-17 



054 



0-G7 



Noon. 



1 



1-44 



1-44 



0-48 



056 



1 P.M. 



2 



1-53 



1-31 



051 



0-68 



2 P.M. 



3 



1-71 



1-56 



0-34 



0-G0 



3 P.M. 



4 



1-35 



1-58 



0-44 



050 



4 P.M. 



5 



1-15 



1-41 



051 



0-42 



5 P.M. 



6 



0-94 



110 



0-91 



068 



6 P.M. 



7 



0-37 



062 



119 



0-90 



7 P.M. 



8 



0-22 



0-37 



1-56 



1-50 



8 P.M. 



9 



029 



0-22 



1-79 



1-87 



9 P.M. 



10 



0-20 



0-17 



2-25 



2-20 



10 P.M. 



11 



0-12 



022 



2-38 



243 



11 P.M. 



12 



049 



0-3S 



2-21 



2-15 



Mid. 



13 



0-47 



0-41 



1-98 



1-74 



1 A.M. 



14 



0-49 



053 



1-80 



1-35 



2 A.M. 



15 



051 



0-71 



1-45 



1-25 



3 A.M. 



1G 



0-97 



101 



095 



0-85 



4 A.M. 



17 



1-53 



0-9G 



0-45 



0-48 



5 A.M. 



For the convenience of those who prefer graphical illustration, I 

 have represented on an accompanying woodcut the results to which 

 I have referred. The curves drawn in unbroken black lines, in figures 

 1 and 2, show the phenomena at Kew ; those in dotted lines in the 

 same figures, the phenomena at Hobarton. Fig. 1 presents westerly 

 disturbances at Kew, and easterly at Hobarton in comparison with 

 each other ; they are obviously allied phenomena. Fig. 2 presents 

 easterly disturbances at Kew and westerly at Hobarton ; these are 

 also, obviously, allied phenomena, but are as obviously governed by 

 distinct laws from those in fig. 1 . 



Had the phenomena at Kew and Hobarton been the only ones 

 known to us, we might have inferred that we had obtained the 

 characteristic forms of the diurnal variations due to the action of two 

 distinct and independent forces ; and we might have expected with 

 some degree of confidence to have found curves of corresponding 

 form by a similar analysis elsewhere ; — and so far experience has 

 been in accord with expectation. But, as the forms of these two 

 pair of curves are not only respectively similar, but as they also 

 correspond in the hours at which their chief characteristic features 

 occur, we might also have formed an inference which would have 

 proved erroneous, viz. that the hours as well as the forms would be 

 the same at other stations. Now this is so far from being in 

 accordance with the facts which we already possess, that whilst the 



