Difference between Animals and Inanimate Machines. 229. We are now able to recognize the difference between the relations to energy of a living being, such as man, and a machine, such as a steam-engine. There are many points in common between the two. Both require to be fed, and in both there is the transmutation of the energy of chemical separation implied in fuel and food into that of heat and visible motion. But while the one-the engine-requires for its maintenance only carbon, or some other variety of chemical separation, the other-the living being-demands to be supplied with organized tissue. In fact, that delicacy of construction which is so essential to our well-being, is not something which we can elaborate internally in our own frames-all that we can do is to appropriate and assimilate that which comes to us from without; it is already present in the food which we eat. Ultimate Dependence of Life upon the Sun. 230. We have already (Art. 203) been led to recognize the sun as the ultimate material source of all the energy which we possess, and we must now regard him as the source likewise of all our delicacy of construction. It requires the energy of his high temperature rays so to wield and manipulate the powerful forces of chemical affinity; so to balance these various forces against cach other, as to produce in the vegetable something which will afford our frames, not only energy, but also delicacy of construction. Low temperature heat would be utterly unable to accomplish this; it consists of ethereal vibrations which are not sufficiently rapid, and of waves that are not sufficiently short, for the purpose of shaking asunder the constituents of compound molecules. 231. It thus appears that animals are, in more ways than one, pensioners upon the sun's bounty; and those instances, which at first sight appear to be exceptions, will, if studied sufficiently, only serve to confirm the rule. Thus the recent researches of Dr. Carpenter and Professor Wyville Thomson have disclosed to us the existence of minute living beings in the deepest parts of the ocean, into which we may be almost sure no solar ray can penetrate. How, then, do these minute creatures obtain that energy and delicacy of construction without which they cannot live? in other words, how are they fed? Now, the same naturalists who discovered the existence of these creatures, have recently furnished us with a very probable explanation of the mystery. They think it highly probable that the whole ocean contains in it organic matter to a very small but yet perceptible extent, forming, as they express it, a sort of diluted soup, which thus becomes the food of these minute creatures. 232. In conclusion, we are dependent upon the sun and centre of our system, not only for the mere energy of our frames, but also for our delicacy of construction-the future of our race depends upon the sun's future. But we have seen that the sun must have had a beginning, and that he will have an end. We are thus induced to generalize still further, and regard, not only our own system, but the whole material universe when viewed with respect to serviceable energy, as essentially evanescent, and as embracing a succession of physical events which cannot go on for ever as they are. But here at length we come to matters beyond our grasp; for physical science cannot inform us what must have been before the beginning, nor yet can it tell us what will take place after the end. INDEX. A. Absorbed Heat. Arts. 123-131, pp. 88-93 Art. 178, p. 128 in its two Forms. Arts. 149-162, pp. 105-118 Action and Reaction, Equal and Opposite. Art. 12, p. 8 Chemical, accompanied by Change of Condition. Art. 167, p. 121 Activity of Molecules. Arts. 10, 11, p. 7 Air and Water in Motion. Art. 203, p. 147 Affinity, Chemical, force of. Arts. 70, 71, p. 53 Electricity probably allied to. Art. 84, p. 65 Hot and a Sounding Body. Art. 162, p. 118 Ancient Ideas not Prolific. Arts. 187, 188, p. 135 Animal a Delicately-constructed Machine. Art. 221, p. 160 Animals and Inanimate Machines, Difference between. Art. 229, p. 165 53-55, p. 39 Aristotle on a Medium. Art. 186, p. 134 Army, Life like the Commander of an. Arts. 222-226, p. 171 Arts. Atmosphere, Resistance and Buoyancy of, disregarded. Art. 30, p. 20 Democritus on. Art. 185, p. 133 Atomic and Molecular Force, Remarks on. Arts. 72-78, p. 51 Forces, how influenced by Heat. Art. 76, p. 58 or Chemical Separation. A t. 111, p. 80 Attraction of Currents. Art. 173, p. 124 |