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XIV. Determinations of the Magnetic Inclination and Force in the British Provinces 
of Nova Scotia and New Brunswich, in the Summer of 1847- 
By Professor George W. Keely, of IVaterville College, Maine, United States. 
Communicated by Lieut. -Colonel Sabine, For. Sec. R.S. 
Received March 1, — Read April 6, 1848. 
In an excursion in the provinces of Nova Scotia and New Brunswick in August and 
September 1847, 1 took with me some magnetical instruments, with which I made a 
few observations for determining the magnetic intensity. The observations were of 
two kinds; those for the relative total force, made with a pair of Lloyd needles, 
which I shall designate L(l) andL(2), and an inclination circle, seven inches in dia- 
meter, with two verniers reading to single minutes, constructed by Barrow, successor 
to Robinson ; and those for the absolute horizontal force, made with a unifilar mag- 
netometer by Jones. The positions of the needles in the inclination circle are deter- 
mined by two reading microscopes with micrometer scales. The unifilar has a theo- 
dolite base and circle of six inches, divided on silver, and reading to twenty seconds. 
Both instruments are described in Captain Riddell’s “ Supplement” to his Mag- 
netical Instructions.” Observations to determine the temperature coefficients of the 
Lloyd needles were made in a small building fastened with nothing but copper, and 
containing a copper stove. For the weights sent by the maker with these needles, 
which were inconvenient, I substituted two platinum weights, which have never been 
removed from the holes in which they were placed before my observations commenced. 
Using t, t', V, v', d, d, (p, <p’ for the temperatures, the angles of deflection, the inclina- 
tions, and the relative forces, respectively, at low and high temperatures, the following 
cos V 
Table exhibits the observations and results by the well-known formula (p=^ ,, , 
I find the results the same whether the mean values of t, v, and &, &c. are used to 
obtain <p and <p', or a mean of the daily results is taken. ? 
2 E 
mdcccxlviii. 
