Popular Lectures and Addresses, Volume 1

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Macmillan and Company, 1891 - Geology
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Page 80 - I often say that when you can measure what you are speaking about and express it in numbers you know something about it ; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind : it may be the beginning of knowledge, but you have scarcely, in your thoughts, advanced to the stage of science, whatever the matter may be.
Page 229 - It is hardly necessary to add that anything which any insulated body, or system of bodies, can continue to furnish without limitation, cannot possibly be a material substance; and it appears to me to be extremely difficult, if not quite impossible, to form any distinct idea of anything capable of being excited and communicated in the manner the Heat was excited and communicated in these experiments, except it be MOTION.
Page 224 - To form some conception of the degree of coarse-grainedness indicated by this conclusion, imagine a globe of water or glass, as large as a football,1 to be magnified up to the size of the earth, each constituent molecule being magnified in the same proportion. The magnified structure would be more coarse grained than a heap of small shot, but probably less coarsegrained than a heap of footballs.
Page 87 - be a greater mistake than that of looking superciliously upon practical applications of science. The life and soul of science is its practical application ; and just as the great advances in mathematics have been made through the desire of discovering the solution of problems which were of a highly practical kind in mathematical science, so in physical science many of the greatest advances that have been made from the beginning of the world to the present time have been made in the earnest desire...
Page 357 - The result would inevitably be a state of universal rest and death, if the universe were finite and left to obey existing laws.
Page 432 - The Electrical Researches of the Honourable Henry Cavendish, FRS Written between 1771 and 1781, Edited from the original manuscripts in the possession of the Duke of Devonshire, KG, by J. CLERK MAXWELL, FRS Demy 8vo. cloth, iSs. Hydrodynamics, a Treatise on the Mathematical Theory of Fluid Motion, by HORACE LAMB, MA, Professor of Mathematics in the University of Adelaide.
Page 357 - It is also impossible to conceive either the beginning or the continuance of life without a creating and overruling power. The author's object was to lay before the Section an application of these general views to the discovery of probable limits to the periods of time, past and future, during which the sun can be reckoned on as a source of heat and light.
Page 101 - Gauss cannot be too much commended, as a great and important practical improvement in the fundamental science of engineering and physics, — the science of dynamics. It consists simply in defining the unit of force as that force which, acting on a unit of mass for a unit of time, generates a velocity equal to the unit of velocity.
Page 397 - In the circumstances, and taking fully into account all possibilities of greater density in the sun's interior, and of greater or less activity of radiation in past ages, it would, I think, be exceedingly rash to assume as probable anything more than twenty million years of the sun's light in the past history of the earth, or to reckon on more than five or six million years of sunlight for time to come.
Page 322 - Some people say they cannot understand a million million. Those people cannot understand that twice two makes four. That is the way I put it to people who talk to me about the incomprehensibility of such large numbers. I say finitude is incomprehensible, the infinite in the universe is comprehensible.

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