H. Crew — Period of Rotation of the Sun. 



209 



v'— ^"=2-173 ±0-028 mi. per sec, 



a velocity some 15 per cent less than that obtained in the first 

 series, viz : 2*565 rni. per sec. But this, as Professor Young has 













Table 



I. 













1 



2 



3 



4 



5 



6 



7 



8 



9 



10 



ii 



.0 





Mean 







Displace- 



Helio- 



~ 2 asin0 



Ave'g. 



Direction of 





o 

 o 

 o 



Date. 



time 



Line. 



a 



CS 



ment. 



centric 

 latitude 



discrep- 



diameter 



i 



fc 





of obs. 





O 



A 



X 





ancy. 



measured. 



£ 







H. M. 







Rev. 







M.p. sec 



% 







1 



July 6 



12 12 



5166-4 



No. 1 



0-0905 



4-4 



2- 



165 



8 



N.W.-S.E. 



50 



2 



June 18 



11 09 



5914-3 



2 



0-1121 



8-1 



2- 



099 



6 



N.W.-S.E. 



20 



3 



July LI 



10 58 



5166-4 



1 



0-0824 



8-9 



1 



990 



11 



N.E.-S.W. 



50 



4 Jurie 19 



11 36 



D, 



1 



0-1076 



14-3 



2 



100 



13 



N.W.-S.E. 



10 



5 



a 



11 50 



" 



" 



0-1116 



15-2 



2 



187 



11 



N.W.-S.E. 



20 



6 



July 6 



11 54 



5166-4 



a 



00843 



16-3 



2 



095 



8 



N.W.-S.E. 



40 



7 



July 3 



11 24 



5914-3 



a 



0-1089 



17-5 



2 



188 



10 



N.W.-S.E. 



20 



8 



June 18 



11 52 



it 



2 



0-0990 



18-3 



1 



932 



12 



N.W.-S.E. 



20 



9 



June 16 



11 33 



D, 



" 



0-1224 



18-5 



2 



410 



14 



N.W.-S.E. 



10 



10 July 11 



10 39 



5166-4 



1 



0-0764 



21-9 



1 



966 



11 



N.E.-S.W. 



45 



11 June 19 



12 14 



D x 



a 



0-0993 



24-0 



■1 



056 



9 



N.W.-S.E. 



18 



12 jJuly 3 



11 36 



5914-3 



a 



0-1023 



24-3 



2 



150 



14 



N.E.-S.W. 



27 



13 July 3 



12 24 



a 



a 



0-1050 



24-4 



2 



210 



15 



N.W.-S.E. 



36 



14 iJune 18 



10 56 



a 



2 



0-0881 



24-8 



1 



799 



12 



N.W.-S.E. 



18 



15 ! July 3 



12 36 



ii 



1 



0-0995 



25-1 



2 



106 



12 



N.W.-S.E. 



27 



16 iJune 18 



12 06 



a 



2 



0-0966 



25-6 



1 



985 



8 



N.W.-S.E. 



18 



17 IJune 19 



12 54 



D, 



1 



0-1044 



30-4 



2 



289 



17 



N.W.-S.E. 



18 



18 June 18 



12 34 



5914-3 



2 



0-0802 



32-5 



1 



763 



10 



N.E.-S.W. 



24 



19 July 6 



12 24 



5166-4 



1 



0-0749 



32-8 



2 



131 



12 



N.W.-S.E. 



40 



20 June 18 



12 22 



5914-3 



2 



0-0920 



39-3 



2 



202 



13 



N.W.-S.E. 



8 



21 



a 



11 21 



" 



" 



0-0871 



39-6 



2 



101 



10 



N.W.-S.E. 



16 



22 



July 3 



11 10 



u 



1 



0-0681 



43-1 



1 



•786 



11 



N.W.-S.E. 



21 



23 



" 



12 03 



ii 



" 



0-0866 



43-6 



2 



291 



11 



N.E.-S.W. 



14 



24 



July 11 



1 06 



5166-4 



a 



0-0415 



45-7 



1 



420 



23 



N.E.-S.W. 



35 



25 



June 18 



1 45 



it 



2 



0-0567 



45-8 



1 



534 



13 



N.E.-S.W. 



21 



26 



July 6 



11 21 



U 



1 



0-0625 



49-6 



2 



300 



6 



N.W.-S.E. 



36 



27 



ii 



12 56 



it 



a 



0-0406 



56-6 



1 



762 



15 



N.W.-S.E. 



25 



28 



July 11 



11 30 



it 



a 



0-0414 



57-1 



1 



824 



18 



N.W.-S.E. 



25 



29 



June 18 



1 32 



it 



2 



00513 



58-8 



1 



872 



16 



N.E-.S.W. 



15 



30 



July 6 



11 05 



a 



1 



0-0457 



58-9 



2 



112 



15 



N.W.-S.E. 



25 



31 



June 19 



12 45 



D, 



" 



0-0621 



60-0 



2 



347 



18 



N.E.-S.W. 



10 



32 



July 6 



10 49 



5166-4 



a 



0-0276 



62-3 



1 



418 



19 



N.W.-S.E. 



25 



33 



July 6 



1 11 



a 



a 



0-0248 



72-1 



1 



932 



30 



N.W.-S.E. 



18 



34 



July 3 



10 58 



5914-3 



a 



0-0300 



72-7 



1-941 



25 



N.W.-S.E. 



9 



pointed out, is just what one would expect, since all the set- 

 tings of the first series were made with the grating " right," 

 and all those of the second with the grating "left." For the 

 heating effect of the sun on the slit-plate will, in the first case, 

 introduce an error with a positive sign, and in the second case, 

 with a negative sign ; hut these errors will not he equal in 

 amount. 



