P. E. Chase on Magnetic Inclination. 167 : 
2. At (magnetically) inter-tropical stations, the dip is dimin- 
ished, but at extra-tropical stations it is increased in the middle 
of the day. 
8. Increasing temperature and increasing solar altitude, aug- 
ment the inclination disturbance. This is shown both by the 
diurnal and the semi-annual curves. 
4. As a corollary of propositions 2 and 3, at St. Helena and 
ay of Good Hope, the inclination-disturbance is opposed to, 
and subtracted from the normal dip; but at Philadelphia, 
Toronto, and Hobarton, the disturbance is added to the dip. 
Thus the inclination is 
a@ minimum at St. Helena, at 22-23h, 
eae “ Cape of Good Hope, “ O- 14, 
“maximum ‘‘ Philadelphia, 22- 0h, 
es “ Toronto, © 99-23b, 
« « —— & ~=Hobarton, “© 93- Th. 
Action of the sun, in increasing the equatorial ellipticity of the 
air, may also increase the tendency to equatorial and polar de- 
eae and the magnetic parallelism may, therefore, be mani- 
a in the solar-diurnal inclination-disturbance precisely as i ts 
at St. Helena and Cape of Good Hope, by a diminu- 
of dip between the parallels of 85°, and an. increase in 
ler latitudes. 
a a 
ti 
ea 
nges, coast lines, land and water radiation, winds, and ocean 
ents modify the theoretical phenomena of dip and declination. 
The motions of fui solids relative to the earth’s surface.” See Ni 
Journal of Medicina 4 oe Oeeey for 1856, and Mathematical Monthly for 1! 
