food, and at such times his attentive and kind sister used to feed him while he went on rubbing glasses. While at times watching the heavens with instruments, he continued patiently to earn his bread by piping to the fashionable frequenters of the Pump-room in Bath.* So eager was he in his astronomical observations, that he would steal away from the room during an interval of the performance, give a little turn at his telescope, and contentedly return to his oboe. Thus working away, Herschel discovered the Georgium Sidus, the orbit and rate of motion of which he carefully calculated, and sent the result to the Royal Society; when the humble oboe player found himself at once raised from obscurity to fame. He was shortly after appointed Astronomer Royal, and by the kindness of George III. was placed in a position of honourable independence for life. He bore his honours with the same meekness and humility which had distinguished him in the days of his obscurity. So gentle and patient, and withal so distinguished and successful a follower of science under difficulties, perhaps cannot be found in the entire history of biography. Sir John Herschel, a son of Sir William, is almost as distinguished an astronomer as his father. From Smiles' Self-Help.' * Bath is frequented for its mineral baths, and also by persons who desire to drink its waters. The Pump-room there is the place into which the more fashionable people go for the latter purpose, and where in the season a band plays. In at least one street in Bath the hot mineral water may be seen bubbling up out of the earth into a fountain, and the vapour rises from it into the air. When the Romans held possession of Britain they often sent their sick persons to the hot springs of Bath to be healed, and they called the city Aqua Solis, or Waters of the Sun, on account of their warmth. SCIENTIFIC SECTION. THE QUALITIES OR PROPERTIES OF MATTER. HERE are certain properties in matter, that is to say certain qualities which are easily perceived by our senses, and these properties or qualities we cannot understand as existing apart from matter. The chief properties of matter are Extension, Impenetrability, Divisibility, Porosity, Density, Inertia, Attraction, Cohesion, Ductility, Malleability, &c. Let us now try to distinguish these properties, although it is often not easy to show the difference between one property and some other. Extension or Magnitude.-We cannot think of matter except as being extended in one direction or another, or as having magnitude or size. For instance, we look in matter for extension in three ways, that is to say length, breadth or width, and depth or height-sometimes however called thickness. Even the smallest object we look at must have these properties, though that object may be too small to be seen by the unaided eye. Impenetrability. This long and not quite accurate word expresses a quality of matter, which is at once easily understood and explained. We are constantly remarking that two bodies or substances cannot fill the same place at the same time. If a pin, for instance, be run into a piece of bread or dough the quality we have called impenetrability still holds good, inasmuch as it is simply "displacement" which has happened. There is no bread or dough occupying the same place as that occupied by the pin, but the particles of the bread or dough are pressed closer together to make a way for it. It has been shown : by chemists, that a measure of water and one of sulphuric acid, when mixed together, occupy less space than the two did when separate. But the explanation of this is easy:we must consider that the particles of the one substance find room in the spaces between the particles of the other. Divisibility.-There is no known limit to the divisibility of matter. A chip of marble may be broken from a block, and that chip may be crushed to powder. The smallest particle of this powder discernible by the naked eye, when examined by the microscope, is seen to be a block having all the qualities of the marble, and capable, by finer instruments, of being divided into still smaller blocks, which may be again divided; and so on, with no other limit than the fineness of our senses and instruments. The unlimited degree to which matter may be divided is yet more strikingly seen in other ways. The thinnest part of a soap-bubble, just before it bursts, was shewn by Newton not to exceed the 2,500,000th part of an inch in thickness. And yet it is evident that the ultimate particles of the water, if there are such, must be of much less diameter than this. The arts present numerous instances of this quality of matter. The gold beater produces leaves of which there are 282,000 in a pile of an inch thick. In making the gilt silver-wire used in embroidery, a rcd of silver is covered with a small proportion of gold, and then drawn out to a fine wire, in which the gold retains the same proportion to the silver as at first. A portion of this wire, on which the gold is only the 432,000,000,000th part of an ounce, may be seen by a microscope to be covered with a continuous coating of the metal, having all the appearance of solid gold. The thinness here far exceeds that of goldleaf. Still more minute must be the division when a substance is dissolved in a liquid, or water rises in vapour, since the particles in this case become so minute as to be invisible with the most powerful magnifiers. The microscope has revealed the existence of animals, a million of which would not occupy more space than a grain of sand. Yet these animalcules, as they are called, have limbs and organs, and display all the appearances of life. How shall we conceive the smallest of the tubes or vessels in which their fluids circulate, and the minuteness of the particles of matter composing these tubes and fluids! But whether the ultimate component particles of bodies have a fixed size and shape or not, we know that they are indestructible. This is not, indeed, what a first impression suggests, for nothing is more common than for bodies to decay, dissolve, evaporate, and disappear. But it can be proved that in no case is anything lost. The structure or form is destroyed, the materials remain. Water, mercury, and many other substances disappear in invisible vapour when heated; but if the vapour is carefully collected and cooled, the water or mercury reappears without loss of weight. When a piece of wood is heated in a close vessel, such as a retort, we obtain water, an acid, several kinds of gas, and there remains a black, porous substance, called charcoal. The wood is thus decomposed or destroyed, and its particles take a new arrangement and assume new forms; but that nothing is lost is proved by the fact, that if the water, acid, gases, and charcoal be collected and weighed, they will be found exactly as heavy as the wood was before distillation. In the same manner, the substance of the coal burnt in our fires is not annihilated; it is only dispersed in the form of smoke or particles of soot, gas, and ashes or dust. Bones, flesh, and other animal substances, may in the same manner be made to assume new forms, without losing a particle of the matter which they originally contained. The decay of animal or vegetable bodies in the open air, or in the ground, is only a process by which the matters of which they were composed change their places, and assume new forms. QUALITIES OR PROPERTIES OF MATTER—continued. The decay and decomposition of animal and vegetable substances beneath the surface of the earth fertilise the soil, which nourishes the growth of living plants; and these, in their turn, form the nutriment of animals. Thus is there a perpetual change from death to life, and from life to death, and as constant a succession in the forms and places which the particles of matter assume. Nothing is lost; and not a particle of matter is struck out of being. The same matter of which every living animal and every vegetable was formed in the earliest ages, is still in exist ence. Porosity and Density.-In common language, a pore is a small hollow space or interstice between the particles of a body, large enough to be seen, or to admit the passage of liquids or gases. In this sense, some substances, such as sponge, wood, sugar, &c., are called porous, and others when contrasted with them are called solid. But experiment and reflection lead us to the conclusion that all bodies are porous. We have seen that bodies are made up of indefinitely small atoms; and the fact that all bodies admit of compression and expansion, makes us believe, that in no case do these atoms fill the whole space occupied by the body, but have interstices of greater or less size between them; so that when a body is compressed, its atoms are only more closely packed. There is nothing, then, that is not porous, in this sense; and one body is more dense or solid than another, only because it is less porous. Density thus means the comparative closeness of the atoms of a body; and a dense body contains, bulk for bulk, more atoms, that is, more matter, than one that is less dense, or, in other words, more porous. As weight depends upon the quantity of matter, density and weight thus go together. Porosity, even in the sense of admitting the passage |