COLONIAL GEOLOGY. 



219 



only profess now to deal, we shall find that they are combinations of the 

 most infusible character, and, a priori, bodies which would be the first con- 

 densed, especially when their strong 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. 



There 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 them " views " — more fully 

 discussed. Mr. Gallaspie however does not give any of the illustrations, with which he 

 says chemistry abounds, of the permanent or rather long-continued production of light 

 and heat by the slow condensation of gaseous 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. What 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 lucifer match, or the rubbing of two sticks toge- 

 ther, shows this. If the heat produced by friction cannot be carried off by the con- 

 ductivity of the atmosphere, it will be accumulated 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 

 accumulation 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, 

 outbalanced, or controlled by the inward tendency of the earth to nearer proximity to 

 the sun. I regret much that space does not permit me to say more in this place. — 

 S. J. Mackie. 27th May, 1864.] 



