nes 
AT MUNICH, 1840, 1841, 1842. 621 
application of the method developed by Mr. Lloyd, that the de- 
flections do not amount to more than 62°, or 400 minutes; so 
that to obtain the intensity to 4,455 would require an exactness 
of a tenth of a minute in the angle, a degree of precision which 
it would be difficult to obtain with certainty in a single deflec- 
tion. We are thus again brought back to the necessity of taking 
greater deflections. 
Although, for these reasons, it is not probable that the method 
proposed by Mr. Lloyd will find an immediate advantageous 
application*, yet the memoir is of great interest, inasmuch as it 
_developes a new method of determining the constants, which 
being improved by future modifications, may, even where not 
absolutely necessary, offer a most highly desirable check. 
It may not be superfluous to examine here the question, at 
what distances the three members of the series suffice, and where 
it becomes necessary to take higher members into the calculation. 
If we say, as above, 
gh 9 orgneg A 
a ey et a ae 
pin igaob ee 
we find 
ey _ gp Ma My | 108: MyM! | 36 M, 
M’ MM’ 2 MM 4 M- 
If we assume the whole magnetism to be in the extremities of 
* Mr. Lloyd’s method would be strictly applicable if, instead of straight bar- 
magnets, horse-shoe magnets were used, thus: 
The magnet would require to be thin and broad, the arms parallel, and the 
extremities of the arms, which (in analogy with the centre of gravity) may be 
termed magnetic centres, inust be in the same horizontal plane. There would 
be no difficulty in the execution; but no material advantage would be gained 
thereby. 
