1876.] Observations made at Stonyhiirst CuUege. 317 



accidentally transposed in the former paper ; but this affected the result 

 as to amount only, and not as to direction. 



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



Eorce. 



Summer 

 months. 



1870. 



1871. 



1872. 



1873. 



1874. 



1875. 



Mean. 



Semiannual 

 mean. 





- 27 



+123 



- 9 



-32 



- 1 



+17 



+0-00118 







May 



- 19 



4- 7 



+ 2 



+ 12 



+ 6 



+35 



+0-00072 







4- 69 



+ 10 



-31 



-31 



- 8 



-33 



-0-00040 





- -0-00010 

















J^iiy 



+ 82 



- 33 



+ 12 



-47 



-26 



-56 



-0-00113 









+ 33 



- 31 



- 3 



-21 



+ 18 



-18 



-0-00037 







September . . . 



-191 



+ 117 



- 9 



-48 



+35 



+60 



-0-00060 







Winter 



1870- 



1871- 



1872- 



1873- 



1874- 



1875- 







Semiannual 



months. 



71. 



72. 



73. 



74. 



75. 



76. 



Mean. 





mean. 



October 



-13 



-24 



+ 16 



-12 



+ 35 



-36 



-0-00057 







November ... 



-41 



+ 26 



+ 26 



-85 



+33 



+ 4 



-0-00062 







December ... 



+20 



+59 



+ 67 



-36 



+40 



+ 11 



4-0-00268 





. -0-00009 

















January 



+ 23 



+ 14 



- 50 



+75 



+48 



-12 



+000163 





February ... 



-31 



+ 38 



- 13 



+ 14 



- 2 



-20 



-0-00023 







March 



-13 



+ 26 



-130 



+ 12 



-39 



—63 



-0-00345 







Yearly means 



- 9 



+28 



- 10 



-17 



+ 12 



- 9 



1 



The probable errors deduced from this Table are +0*0033 for each 

 monthly determination, and + 0'0004 for the resulting mean. 



The Magnetic Dip. 



Table I. — Monthly mean values of the Dip. 



Summer 

 months. 



1870. 



1871. 



1872. 



1873. 



1874. 



1875. 



Mean 

 of six 

 years. 



April 



69 33 6 



69 35 12 



69 33 15 



69 29 13 



69 27 55 



o 



69 19 58 



69 29 47 



May 



40 25 



33 17 



29 19 



32 10 



23 4 



21 37 



29 59 





37 47 



32 33 



31 24 



30 11 



28 50 



21 35 



30 23 



July 



39 30 



32 55 



29 56 



28 34 



27 54 



20 8 



29 50 



August 



36 36 



32 57 



29 31 



33 45 



25 51 



22 21 



30 10 



September . . . 



40 26 



30 57 



32 8 



30 



[ 26 14] 



24 8 



30 39 



Means 



69 37 58 



69 32 59 



69 30 56 



69 30 39 



69 26 38 



69 21 38 



69 30 8 



