COLONIAL GEOLOGY. 
219 
only profess now to deal, we shall find that they are combinations of the 
most infusible character, and, a ptnori, bodies which would be the first con- 
densed, especially when their stronoj affinities are taken into consideration. 
And those bodies which are easily dissipated by heat are almost wholly ex- 
cluded, such as water, carbonic acid, etc, 
TLere is another argument I wish to point out, which I think is 
erroneous. You suppose that the heat of the earth is sufficiently accounted 
for on the grounds of its retardation through the ether of space. A little 
reflection will show that a body once heated to its maximum temperature, 
from whatever cause, whether in passing through air or the ether of space, 
if the medium be uniform in resistance and the motion constant, the 
heated body must necessarily diminish in temperature until it is reduced 
to the same degree of heat as the medium through which it passes. The 
reasons are obvious. The original cause of heat in the case supposed is 
ethereal resistance, and the moving body eliminating heat is in consequence 
of the rearrangement of its constituent particles adjusting themselves to 
their altered condition ; and when this is attained the heated body must 
sink again to its normal condition of heat, and could not, I think, per- 
manently retain a heat so much superior to the medium through which it 
moves, simply in consequence of resistance. 
I am, Sir, most respectfully yours, 
Thos. Gallaspie. 
[I am very glad to have my suggestions — I do not call tlicm "views" — more fully 
discussed. Mr. Gallaspie however does not give any of the illiistratious, with which he 
8a_vs cijeniistry abounds, of the permanent or rather long-conliiiucd production of light 
and heat by the slow condensation of (/aseous bodies. Take oxygen and hydrogen. 
They combine with explosion. The heat, I conceive, which drove these particles apart 
whilst they were gases, has passed off into the air, and become motion acting upon the 
particles of the atmosphere. The resulting produce is a drop of water, not boiling. 
Shales and metals are solid substances ; and even if we take metallic vapour, what should 
cause metallic vapour to exist in space? Where is the heat to come from anywhere 
except within the circuit of our earth's orbit, which should raise gold, iron, or even tin 
and lead into vapour. There seems to me not a particle of scientific evidence nor of pro- 
bability in favour of the nebular hypothesis — such it was first properly termed, such it 
still, to my mind, remains. 
The other point as to the effect of the resistance of the ether of space — although I do 
not agree with Mr. Gallaspie — is better put. The point raised by me was this: if the 
earth's motion in her orbit be due to any original impetus given to our planet, then the 
resistance of the ether of space to the earth's motion must give rise to friction, and this 
friction must be, by the laws of the correlation of the physical forces, be changed into 
some other force than motion. AVhat is lost by friction as motion must become heat, 
light, electricity, chemical, or molecular action. As to what is the temperature of space, 
we have yet to learn what that temperature is in the area of the earth's orbit. Mr. 
Gallaspie should bear in mind that if this heat of our portion of space be due to the heat 
of the sun, it can be estimated. But certainly friction may raise a body, gaseous or 
solid, to, and maintain it at a higher temperature than the surrounding air or gaseous 
medium. The production of fire by a lueiter match, or ths rubbing of two sticks toge- 
ther, shows this. If the heat produced by friction cannot be carried oft' by the con- 
ductivity of the atmosphere, it will be accunmlated in the object. As the orbital speed of 
the earth is, on the spiral-orbit hypothesis, slowly and constantly diminishing, there should 
be thus consequently a slow and constant diminution of the heat acquired by the past 
accumulatioa from higher friction— that is practically a slight cooling of the globe 
throughout past ages, and at present going on. The amount of this would be negatived, 
outbaranced, or controlled by the inward tendency of the earth to nearer proximity to 
the sun. 1 regret much that space does not permit me to say more in this place. — 
S. J. MACKiii. 'Zlth May, 18G4,.] 
