HorIzONTAL FORCE. XX1x 
may also derive results from Table 10 similar to those derived from Table 5. It 
will be observed from the former Table that the months June, July, and August 
comport themselves in the same manner. From between 17° and 18", to about 
0* Gottingen mean time, viz., from between 4 a.m. and 5 A.M. to about 11 a.m. 
Makerstoun mean time, they are affected with a negative sign, or have a less 
than average horizontal force, while for the remaining hours they are affected 
with a positive sign, or have a greater than average horizontal force. Nearly 
the opposite happens with the two months November and December. From 
about 13° to 1" Gottingen mean time, viz., from about midnight to noon Maker- 
stoun mean time, they are affected with a positive sign, or have a greater than 
average horizontal force; while during the remainder of the day they are af- 
fected with a negative sign, and have a less than average horizontal force. If 
from Table 10 we deduce the annual variation for the mean of the day, that is 
to say for the mean of all the hours, we shall obtain a result similar to that de- 
duced by Mr Broun from part of the series of years used in Table 10, viz., that the 
horizontal force is a maximum at the solstices and a minimum at the equinoxes. 
