MAGAZINE OF SCIENCE AND ART. 
175 
clouds, or perhaps only in cumulose clouds in which 
subsidence of aggregation of the cloudy particles is going 
on, because the curaulose action is the sole cause of the 
collection and concentration of the electricity. This 
agrees well, so far as I can understand, with the con¬ 
clusions of Arago in his “ Essay on Thunder and Light¬ 
ning,’ 
The atmosphere is almost always electrical in one kind 
or the other. Whenever cumulose precipitation takes 
place in a very excessive and concentrated manner, we may 
therefore expect lightning, but this will not necessarily 
follow, since the air may not, at the time, happen to be 
sufficiently electrified. 
77. Of all physical subjects, one of the most backward 
and obscurely understood is that of atmospheric electricity. 
Any theory of thunderstorms must, therefore, be very 
crude as regards the electrical part of the phenomena, and 
we must not be discouraged, if a theory of the clouds 
constructed upon dynamical principles and the known rc 
actions of air, water, and heat, although giving a plausible 
general explanation of another class of ill understood 
phenomena, does not, at first, comprehend every fact or 
reconcile every difficulty of the latter. 
Thus a serious objection to the above theory will at 
once suggest itself to many persons, namely, that in a 
thunderstorm the kind or ,$ijn of the electricity often 
changes in a most capricious and inexplicable manner from 
positive to negative, of frtim negatve to positive. My 
theory certainly does. not include or presuppose such 
changes, but I cannot see that it excludes them. A great 
thunderstorm is a very extensive affnr. There are 
probably many foci or parts of the cloud where the 
ascending or cumulose action goes on with greatest 
energy. in the intermediate parts the action is different. 
Some of the air which has ascended at the foci mav here 
descend or perhaps carry down bodies of air from higher 
parts of the atmosphere, where the electric charge is of 
the opposite kind or might be so converted by the induc¬ 
tive action of neighbouring masses of highly electrified 
cloud. 
Or it is a more probable suggestion, I think, that 
among a number of cumulose foci some may be Sup¬ 
plied with moist electrified air from one source, and 
ethers from quite a different current of air. A con¬ 
siderable thunderstorm produces a great commotion in 
the atmosphere, and winds may blow towards it from 
every point of the jomp.issj and it is far from im¬ 
probable that the electricity of some currents will be 
opposite in kind to that of the others. 
but I repeat that as my theory is in no way founded 
on an electrical basis, so it docs not pretend at fir*t to 
comprehend all the facts of that most remarkable and 
capricious of physical principles, electricity. 
Agf.sct of Electricity is the Atuospiiebe. 
7S. It is a common belief that electricity cxertsa very 
active agency in the atmosphere ; that it is. in short, the 
fourth element of Meteorology, of which the first three 
as was explained ( 4 , are Air. Water, and the agent Heat! 
If, without assuming that the theories above propounded 
are actually correct, we only admit that they lie in the 
right direction and appear to rest upon some sound basis 
there is one inference which can be so plainly drawn that i 
cannot resist making a few remarks upon it The agency 
of electricity in the atmosphere I believe to be a cmnlete 
fallacy. 1 
79. It would appear that the wonderful effects wide!, 
electricity in one or other of its forms often exhibit- 
have led to a style of speculation entirely at variance with 
all rules of inductive reasoning. And I do not make this 
remark with regard to Meteorology alone ; for instance 
every one can remember the absurd opinions which were I 
entertained a short time since about table iurniun, and 
were entertained by such numbers or respectable persons as 
to be thought worthy of serious refutation by iaradav 
Mesmensm Electro biology, and other disputed questions, 1 
whatever the true mental phenomena upon which they I 
“7 7, have all in their day obtained ascendancy I 
and afterwards fallen into disrepute, because tiicy were 1 
propounded in a pseudo-scientific form, and, at the same 
No. 8. Jan. 1858. 
time, appealed to the mysterious and imaginative proper¬ 
ties with which most persons invest electricity. in many 
cases, certainly, electricity produces practical effects which 
are noth ing short of miracles to the finite mind of man, 
but it does not therefore follow that he may dispense with 
observations and reasoning, and ascribe other miraculous 
effects to electricity at random, 
79. Now in Meteorology the case has hitherto been very 
little different, and, in the subject of the clouds especially, 
the electrical Imagination, which is found even In scientific 
men, has had full play and produced a multitude of 
absurd theories. The .Meteorologist Howard thought, in 
18-0. that tho cirrus miff lit be produced by elecrical repul¬ 
sions, and the same conjecture has been published in 
every work on the subject up to the present day. The 
form of the cumulus he even attempted to explain by 
elrctrical attractions and repulsions, cud in almost all des¬ 
criptions or theories of thunderstorms we read of clouds 
attracting and repelling each otner, as if nothing but 
electricity could produce their motions. 
The now work of Lieutenant Maury on the *' Physical 
Geography of the Sea” contains one of the worst examples 
of these vicious theories ; for the safest conjecture which 
ho can offer, as the result of the splendid system of obser¬ 
vation of which he is the head, is that the winds are 
probably directed in their course by terrestrial maa- 
netism. As a general rule we may look upon all electrical 
Iheories as utter nonsense, 
80. Sound investigation will Invariably tend to show, I 
think, that all the forms and phenomena of clouds, indeed 
the whole phenomena with which Meteorology is occupied 
consist in motions and changes which are the simple 
eflects of heat upon air and water. Air undergoes changes 
of density, amt water undergoes alternate changes from 
the gaseous to the liquid or solid state, and these are the 
widest and almost the only generalizations upon which 
Meteorology is founded, and from which its infinite com¬ 
plexity of phenomena must be derived, just as the science 
of Astronomy is founded on the simple but universal law 
of gravitation, which is but little more than an expression 
of perfect generality for the infinitely various configura¬ 
tions which the heavenly bodies exhibit to a terrestrial 
observer. 
SI. Hut Electricity has no place among the principles of 
Meteorology it is but a secondary or accidental result of 
thosd principles, just as day and night, summer and winter 
and many others of the conditions of Meteorology are Hie’ 
secondary effects of A stronomical laws. 
By a secondary effect 1 mean one which is of a different 
order from its cause, and cannot produce any appreciable 
reaction. < fi.mges, for instance, in the atmosphere can¬ 
not affect the sun although his healing rays are their 
principal cause. The greatest flashes of lightning, the 
intensest signs of atmospheric electricity, scarcely more, 
ill my opinion, affect the motions of air and clouds, or the 
processes of evaporation and condensation, which arc 
doubtless the source of electrical excitation. 
To this conclusion we ate naturally lead by the pre¬ 
ceding arguments, as to tile cuuses of clouds, for we find 
thul iheir various distinct forms can be accounted for by 
simple motions originating in the actions and reactions of 
.ir, water, and heat, and there remains, as it were, do 
room tor the agency of eUctricity, 
To show that this conclusion is probable on general 
grounds, I need only quote a sentence from the highest 
philosophical authority, Sir .1. Herseliei, (i.ssays, &.• •• 
Page “ Here also wo have to deal with electricity 
a thiru element, but wc strongly incline to the opinion 
that its agency as a meteorological cause is exceedingly 
limited, inded that It may be altogether left out of the 
account as productive of any meteorological efiect of irn- 
portaooe on the great scale." 
8d. To make the relation of electricity to the atmosphere 
plainer. I will conclude with a further example: Thou-h 
few persons ha e, I suspect, witnessed the phenomenon, it 
is staled in electrical treatises that when the b.ck of a 
domestic eat is smartly rubbed, crackling sparks of elec¬ 
tricity are emitted. in this case, friction is undoubtedly 
the cause of the electricity, but.would any one be fool,.,., 
enough to say that electrical 3itraction was in any way of 
