1876.] Observations made at Stony hurst College. 321 

 The figures in this Table give for the epoch April 1st, 1873 — 



The mean Declination = 21° 20' 27" W. 

 "With a secular variation of — 9' 27". 



As might be suspected from the geographical positions^ this amount 

 of secular diminution is somewhat in excess of that found at Kew for the 

 same epoch, which was —8' 5" "72. 



Table II. — Semiannual inequality of the Declination. 



Correction 

 for secular 

 variation. 



Mean 

 value 

 + secular 

 variation. 



Observed, 

 values. 



+25 59 



21 46 26 



O , 



21 41 50 



+21 15 



41 42 



44 10 



+16 32 



36 59 



33 28 



+ 11 49 



32 16 



30 29 



+ 7 5 



27 32 



23 45 



+ 2 22 



22 49 



26 28 



- 2 22 



18 5 



20 30 



- 7 5 



13 22 



15 46 



-11 49 



8 38 



8 44 



-16 32 



3 55 



8 42 



-21 15 



20 59 12 



20 57 32 



-25 59 



54 28 



54 



Date. 



Observed— Calculated. 



Summer, i Winter. 



July 1, 1870.... 



Jan. 1, 1871. 

 July 1, 1871.... 



Jan. 1, 1872. 

 July 1, 1872.... 



Jan. 1, 1873. 

 Julyl, 1873.... 



Jan. 1, 1874. 

 July 1, 1874.... 



Jan. 1, 1875. 

 Julyl, 1875.... 



Jan. 1, 1876. 



-4 36 

 -3 31 

 -3 47 

 +2 25 

 +0 6 

 -1 40 



+2 28 

 -1 47 

 +3 39 

 +2 24 

 +4 47 

 -0 28 



Mean differences in the semiannual periods. 



1 50-5 +1 50-5 



Here again the winter is in excess of the summer period, the annual 

 variation being 3' 41". This agrees also with the Kew results ; but the 

 amount found by Mr. Whipple is only 1' 21"*80. 



Table III. — Eesidual errors in the monthly values of the Declination. 



bummer 

 months. 



1870. 



1871. 



1872. 



1873. 



1874. 



1875. 



Mean. 



Semi- 

 annual 

 mean. 



April 



May 



June 



July 



August . . . . 

 September . 



-3 20 

 -7 23 

 +2 21 

 -4 48 

 -0 8 

 -3 16 



+5 2 

 -4 28 

 -3 11 

 -6 24 



-3 37 

 +2 33 



-5 45 

 -3 

 -5 1 

 -2 21 

 +3 4 

 + 2 21 



+2 29 

 +4 3 

 +3 3 

 +2 38 

 +8 13 

 +4 2 



-5 34 

 +0 2 

 +2 14 

 + 6 26 

 +2 30 

 +5 56 



+0 15 

 -4 11 

 +1 41 

 +0 19 

 -1 30 

 +4 40 



-1 6 

 -2 30 

 +0 11 

 -0 42 

 +1 25 

 +2 43 



0-2 



2 a2 



