36 W. A. Norton on the Variations of the Declination 
in the relative intensities of the two systems of currents. In th 
summer the radial currents are more efficient than the eclipti 
but in the winter the ecliptic currents are much more efficient that 
the radial ; and the tendency of the radial currents is to produc 
a minimum early in the forenoon, and of the ecliptic currents t 
uce a minimum at noon. It follows therefore that the act 
Eo Aiteore should occur later in the forenoon in the winter tha 
in the summer. 
The increase in the mean monthly value of the horizontal for 
from the winter to the summer solstice, finds its explanation in th 
coe action of the ecliptic currents. In the course of a sing 
day the diminution and augmentation of the horizontal force t 
result from the action of the radial currents balance each othe 
and hence the popes in the mean daily values of this fo 
th to another, must be ascribed to the annual v 
rom one 
ation of the e€ Now these currents have the high 
est intensity in nter (p. 35), and always tend to dimm! 
the horizontal fore the mean daily value of this fo 
ical results furnish a stron wn oa of the troth, of this e 
planation. Mean annual intens yoft 
One, for the years 1843-8, ( or mean of the 
tos * mae intensity of sal Mia 
aie Feb., March, Sept., Oct., Nov., and Dec.= 94: 
tensity for “April, May, June, Joly, and Ang.= 49-0. Fro ” 
941—753=188; 753—49-0=26:3. Again mean vibe “of hori 3 : 
zoptal force, at Toronto, from 1845 to 1851, (allowing for sect 
lar change, Toronto Observations, vol. ii, p. 91)=3: 53088 ; m 
horizontal force for the months of Jan., Feb., March, Sept., Oct. 
Nov., and Dec. =3-52973 ; mean hotizdntal force for April, May, 
June, July, and Aug. =3- 53250. Whence 3.53088—3:52973= _ 
OOLIS ; 3°53250—3-53088=-00162. Now -00162~-0011 
1:409 ; and 263+18-8=1-400. From Sept. to March, inclusiv 
the ecliptic currents are the most energetic, and have pretty nea 
the same intensity. ‘The intensity in April is as high as the low 
est intensity during this interval. If we include April in 
months of highest : intensity, that is compare January, Februa 
March, April, September, October, November, December, W 
May, June, July, August, we have a still closer agreemen 
results, for the quotients come out respectively 2:00, and M 
VERTICAL FORCE. 
Diurnal and Annual Variations.—It is first to be obse 
that, agreeably to the general theory which is under consideration, 
the dinrnal and annual variations of the vertical force are to © 
referred entirely to variations in the intensity of the ecliptic 
rents. ‘The radial currents which aoe from any point of 
