Various

“ All the properties of matter are so connected that we can scarcely imagine one thoroughly explained without our seeing its relation to all the others, without in fact having the explanation of all; and till we have this we cannot tell what we mean by "explaining a property" or "explaining the properties" of matter. But though this consummation may never be reached by man, the progress of science may be, I believe will be, step by step toward it, on many different roads converging toward it from all sides. The kinetic theory of gases is, as I have said, a true step on one of the roads. ”

“ No liquid has nearly so wide a range of dissolving powers, and, taking things all round, no liquid exercises so slight an action upon the bodies dissolved—evaporate the water away, and the dissolved substance is obtained in an unchanged condition; at any rate, this is the general rule.
The function of water in nature is essentially that of a solvent or a medium of circulation; it is not, in any sense, a food, yet without it no food can be assimilated by an animal. Without water the solid materials of the globe would be unable to come together so closely as to interchange their elements ”

“ The strange power we call "life," doubly mysterious when manifested in an organism so simple as this, so open to our search, seems to challenge us to discover its secret, and, armed with our glittering lenses and our flashing stands of exquisite workmanship, we search intently, but in vain. And yet not in vain, for we are more than recompensed by the wondrous revelations beheld and the unalloyed pleasures enjoyed, through the study of even the unpretentious Vaucheria. ”

“ Now Joule's and my own old experiments on the efflux of air prove that if the crowd be common air, or oxygen, or nitrogen, or carbonic acid, the temperature is a little higher in the denser than in the rarer condition when the energies are the same. By the hypothesis, equality of temperature between two different gases or two portions of the same gas at different densities means equality of kinetic energies in the same number of molecules of the two. From our observations proving the temperature to be higher, it therefore follows that the potential energy is smaller in the condensed crowd. ”

“ As a step toward kinetic theory of matter, it is certainly most interesting to remark that in the quasi-elasticity, elasticity looking like that of an India-rubber band, which we see in a vibrating smoke-ring launched from an elliptic aperture, or in two smoke-rings which were circular, but which have become deformed from circularity by mutual collision, we have in reality a virtual elasticity in matter devoid of elasticity, and even devoid of rigidity, the virtual elasticity being due to motion, and generated by the generation of motion. ”

“ Thus, after all, the train of speculation suggested by Davy's "Repulsive Motion" does not allow us to escape from the idea of true repulsion, does not do more than let us say it is of no consequence, nor even say this with truth, because, if there are impacts at all, the nature of the force during the impact and the effects of the mutual impacts, however rare, cannot be evaded in any attempt to realize a conception of the kinetic theory of gases. ”

“ It might be imagined that the action at a distance thus provided for by fluid motion could serve as a foundation for a theory of the equilibrium, and the vibrations, of elastic solids, and the transmission of waves like those of light through an extended quasi-elastic solid medium. But unfortunately for this idea the equilibrium is essentially unstable, both in the case of magnets and, notwithstanding the fact that the forces are oppositely directed, in the hydro-kinetic analogue also, when the several movable bodies (two or any greater number) are so placed relatively as to be in equilibrium. ”

“ In conclusion, I wish to paint out that the practice adopted at some collieries, of having all the men supplied with the most approved lamp (such as the Mueseler or tin shield lamp) is not a safe one. If the strength of a chain is only equal to the weakest link, it may be argued that the safety of a mine is only equal to that of the most careless man or most unsafe lamp in it. ”

“ Thus, at any time the actual motion of the liquid at any point in the neighborhood of the solid will be the resultant of the motion it would have in virtue of the circulation alone, were the solid at rest, and the motion it would have in virtue of the motion of the solid itself, had there been no circulation established through the aperture. It is interesting and important to remark in passing that the whole kinetic energy of the liquid is the sum of the kinetic energies which it would have in the two cases separately. ”

“ We find it to be the general opinion at present, as it perhaps has always been among lumbermen and those who work among timber, that the sap of a tree is an evil which must be avoided if possible, for it is this which causes decay and destroys the life and good qualities of all wood when allowed to remain in it for an unusual length of time, but that this is a mistaken idea I will endeavor to show, not that the decay is due to the sap, but to the time when the tree was felled. ”

“ If we look at our modern manufactures immediately after studying patterns which enchant us with their classical repose, or after it such others as captivate the eye by their beautiful coloring, or the elaborative working out of their details, we recognize that the beautifully balanced form is often cut up, choked over with others, or mangled (the flower springing up side down from the leaves) , the whole being traversed at random by spirals, which are utterly foreign to the spirit of such a style, and all this at the caprice of uncultured, boorish designers. ”

“ In these illustrations and models we have different portions of ideal rigid matter acting upon one another, by normal pressure at mathematical points of contact—of course no forces of friction are supposed. It is exceedingly interesting to see how thus, with no other postulates than inertia, rigidity, and mutual impenetrability, we can thoroughly model not only an elastic solid, and any combination of elastic solids, but so complex and recondite a phenomenon as the passage of polarized light through a magnetic field. ”

“ Thus it will be seen that rain tends to wonderfully clear or wash the atmosphere, and we all know how much a first rain is appreciated as an air purifier, and how it carries down with it valuable food for plants. The rain-water, in percolating through or over the land, flows mainly toward the rivers, and in doing so it becomes more or less charged with mineral matter, lime salts and common salt being the chief of them; while some of that water which has penetrated more deeply into the earth takes up far more solid matter than is ordinarily found in river water. ”

“ Let us, then, leave the kinetic theory of gases for a time with this difficulty unsolved, in the hope that we or others after us may return to it, armed with more knowledge of the properties of matter, and with sharper mathematical weapons to cut through the barrier which at present hides from us any view of the molecule itself, and of the effects other than mere change of translational motion which it experiences in collision. ”

“ And in fact, unless we are satisfied to imagine the atoms of a gas as mathematical points endowed with inertia, and as, according to Boscovich, endowed with forces of mutual, positive, and negative attraction, varying according to some definite function of the distance, we cannot avoid the question of impacts, and of vibrations and rotations of the molecules resulting from impacts, and we must look distinctly on each molecule as being either a little elastic solid or a configuration of motion in a continuous all-pervading liquid. ”

“ Literature relating to turbines probably stands unrivaled among all that concerns questions of hydraulic engineering, not so much in its voluminous character as in the extent to which purely theoretical writers have ignored facts, or practical writers have relied upon empirical rules rather than upon any sound theory. In relation to this view, it may suffice to note that theoretical deductions have frequently been based upon a generalization that "streams of water must enter the buckets of a turbine without shock, and leave them without velocity." ”

“ When we look upon water as the nearest approach to a universal solvent that even the astute scientist of to-day has been able to discover, who can wonder that it is never found absolutely pure in nature? For wherever it accumulates it dissolves something from its surroundings. Still, in a rain-drop just formed we have very nearly pure water; but even this contains dissolved air to the extent of about one-fiftieth of its volume, and as the drop falls downward it takes up such impurities as may be floating in the atmosphere ”

“ Between the action of turbines and that of screw propellers exists an exact parallelism, although in one case water imparts motion to the buckets of a turbine, while in the other case blades of a screw give spiral movement to a column of water driven aft from the vessel it propels forward. Turbines have been driven sometimes by impact alone, sometimes by reaction above, though generally by a combination of impact and reaction, and it is by the last named system that the best results are now known to be obtained. ”

“ Hence, we must infer that the proper time for felling the tree is when the conditions are such that the rapid decay of a new growth of wood is impossible; and this I have found by experiment to be in early summer, after the sap has ascended the tree, but before any new growth of wood has been formed. The new growth of the previous season is now well matured, has become hard and firm, and will not decay. On the contrary, the tree being cut when such new growth has not well matured, decay soon takes place, and the value of the timber is destroyed. ”

“ He found from an investigation which he conducted with much care during a visit to London that it is undoubtedly true that large fires are much less frequent in the metropolis than in American cities; but it is equally true that the circumstances existing in London and New York are quite different. As it is a well-known fact that the promptness, efficiency, and bravery of American firemen cannot be surpassed, we gladly give prominence to the result of the author's investigations into the true causes of the great liability of American cities to large fires. ”

“ The mutual action at a distance, repulsive or attractive according to the mutual aspect of the two bodies when passing within collisional distance10 of one another, suffices to produce the change of direction of motion in collision, which essentially constitutes the foundation of the kinetic theory of gases, and which, as we have seen before, may as well be due to attraction as to repulsion, so far as we know from any investigation hitherto made in this theory. ”

“ But at a time when dyeing, spinning, and weaving were, if not in the one hand, yet at any rate intimately connected with one another in the narrow circle of a home industry, the appearance of this beautiful gold-yellow plant, heaped up in large masses, would be very likely to suggest its immortalization in textile art, because the drawing is very faithful to nature in regard to the thorny involucre. ”

“ For some guidance toward a deeper and more comprehensive theory of matter, we may look back with advantage to the end of last century and beginning of this century, and find Rumford's conclusion regarding the heat generated in boring a brass gun: "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;" ”

“ It is convenient, however, in the kinetic theory of gases, to adopt arbitrarily a precise definition of collision, according to which two bodies or particles mutually acting at a distance may be said to be in collision when their mutual action exceeds some definite arbitrarily assigned limit, as, for example, when the radius of curvature of the path of either body is less than a stated fraction (one one-hundredth, for instance) of the distance between them. ”

“ Rich as it is in practical results, the kinetic theory of gases, as hitherto developed, stops absolutely short at the atom or molecule, and gives not even a suggestion toward explaining the properties in virtue of which the atoms or molecules mutually influence one another. ”

“ Investigations the object of which is to clear up this process of development as far as possible are likely to be of some service; a person is more likely to recognize the beauties in the details of ornamental works of art if he has an acquaintance with the leading styles, and the artist who is freed from the bondage of absolute tradition will be put into a better position to discriminate between accidental and arbitrary and organic and legitimate forms, and will thus have his work in the creation of new ones made more easy for him. ”

“ These alterations in pressure can only be eliminated when care is taken to measure that only due to impact, without at the same time adding the effect of an imperfect reaction. Any stream that can run off at all points from a smooth surface gives the minimum of pressure thereon, for then the least resistance is offered to the destruction of the vertical element of its velocity, but this freedom becomes lost when a stream is diverted into a confined channel. ”

“ There are men still alive who no doubt could clear up the question at issue, and it is much to be hoped that they will do so. As the matter now stands, it will be seen that we do not so much question that the Rocket in South Kensington Museum is, in part perhaps, the original Rocket of Rainhill celebrity, as that it ever ran in regular service on the Liverpool and Manchester Railway. ”

“ Yet, when this is examined under the magic tube, a crystal cylinder, closely set with sparkling emeralds, is revealed. And although so transparent, so apparently simple in structure that it does not seem possible for even the finest details to escape our search, yet almost as we watch it mystic changes appear. We see the bright green granules, impelled by an unseen force, separate and rearrange themselves in new formations. Strange outgrowths from the parent filament appear. ”