48 DR. FARADAY’S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XXVI.) 
assumption is not too extravagant for an illustration, since Prout showed that there 
were masses of air, larger or smaller, floating about in the atmosphere, and singularly 
distinct from the surrounding parts, by temperature and other circumstances. Not to 
complicate the expression, we will leave out of view, at present, the attenuation up- 
wards, and will consider one of these globes as colder or denser than the contiguous 
parts, and that it is in a portion of space which without it would present a field of 
equal magnetic force, i. e. having parallel lines of equal intensity of force passing 
across it. 
2865. The air of such a globe will facilitate the transmission of the magnetic force 
through the space which it occupies (2807.), making it superior, in that respect, to 
the surrounding atmosphere or space, and therefore more lines of magnetic force will 
pass through it than elsewhere (2809.). The disposition of these lines, in respect of 
the line of the dip of the place, will be something like what is represented in fig. 7, 
(2874.), and consequently the globe will be polarized as a conductor (2821. 2822.) 
of the paramagnetic class. Hence the intensity of the magnetic force and its direction 
will vary, not only within but without the globe, and these will vary in opposite direc- 
tions, in different places, under the influence of laws which are perfectly regular and 
well known. 
2866. First, as regards the intensity, which before was uniform (2864.). If the in- 
tensity is to be considered as expressing the amount of force which passes through 
any given place, then, in consequence of the definite amount of power which belongs 
to any section, as a a, of a given amount of lines of magnetic force (2809.), a concen- 
tration of these lines towards the middle, P, will cause an increase of intensity at that 
part, and a diminution at some other parts, as b h, from whence the influence of the 
power has been partly removed. Hence, supposing the normal condition to exist at a, 
if a test of intensity were carried from a to P, it would gradually enter parts b and c, 
in which the intensity was less than the normal condition, and these might be either 
without or within the globe P, or both (according to its temperature relative to the 
surrounding air, its size and other circumstances); it would then arrive at parts 
having the normal intensity ; and lastly, at parts, P, having an intensity greater than 
the surrounding space ; as it went outwards, on the opposite side of P, corresponding 
variations would occur in the reverse order. 
2867- On transporting the test upwards, in the direction of the dip from e, where 
the intensity may be considered as normal, it would gradually occupy positions at 
f g, Sec., in which the intensity would increase until it arrived at P, after which it 
would pass through places of less and less intensity, until at p it would again find 
the force in the normal state. If the test, in being carried upwards, be not taken 
along the line of the dip, then it will of course pass through variations like those de- 
scribed on the line a P, growing more and more in extent until the direction coincides 
with the line a P, which is at right angles to the dip and where they are at a maximum. 
Hence, to pass upwards through such a globe of cold air in our latitude, where the 
