47 
the intensity of magnetic forces , &c. 
To reduce these observed positions of the points of equili- 
brium to their true positions, that is, those which they would 
have had if the temperature of the magnets had been the 
same at each of the observations, it is necessary to apply a 
correction by means of Tables I. and II. ; and that the nature 
of this reduction may be evident, I shall give an instance of 
the process at length of applying the tables to the correction 
of the observations, when the temperature at which they 
were made was belozu the standard temperature, and also 
when it was above that temperature. As the observations 
were made with the magnets at temperatures varying nearly 
equally above and below 6 o°, I consider that, the standard 
temperature to which to reduce them. The two following 
are instances of this reduction. 
1st. Observed temperature below the standard temperature. 
24th May, 6 ^ 00™ A. M. 
Westerly. 
Easterly. 
Points of Equilibrium 
83° 27 
83 1 1 at temp. 570 
Correction for 1° Temp. Table II. 
— 47.002 
— 45-397 
Points of Equilibrium • 
82 39.998 
82 25.603 at temp. 58° 
Correction for 1® Temp. 
— 42.581 
— 41.380 
Points of Equilibrium 
81 57.417 
81 44.223 at temp. 59® 
Correction for 1° Temp. 
— 39-244 
— 38.316 
Reduced Poiuts of Equilibrium 
81 18.173 
81 05.907 at standard temp. 60°. 
2nd. Observed temperature above the standard temperature. 
29th May, Noon. 
Westerly. 
Easterly. 
Points of Equilibrium 
820 00' 
81034^ at temp. 63° 
Correction for 1° Temp. Table I. 
4- 42.820 
+ 40-5*7 
Points of Equilibrium 
82 42.820 
82 14.5 17 at temp. 62® 
Correction for 1® Temp. 
+ 47-329 
+ 44-241 
Points of Equilibrium 
83 30.149 
82 58.758 at temp. 610 
Correction for i® Temp. 
+ 53 - 7*3 
+ 49-296 
Reduced Points of Equilibrium 
84 23.862 
83 48.054 at standard temp. 60®. 
