rates of wages in different trades. Why, for example, does a machine-maker obtain higher wages than a mason? The answer is-Because the demand for machine-makers is greater in proportion to the supply of such workmen than the demand for masons in proportion to the supply of masons. But why, it may be asked, are machine-makers fewer in proportion to the demand for them than masons? Why is there a difference in the supply of hands in different trades? To this question the answer is, that some trades are more difficult to acquire, or demand higher qualifications than others. The work of a physician, for example, is much more difficult, and requires far higher qualifications, than the work of a carpenter; and the work of a carpenter, again, is harder to learn, and demands more knowledge and skill, than that of a ploughman. Now, the difficulty of acquiring and exercising a profession or trade necessarily limits the number of persons who enter it; and this, accordingly, is one, and probably the chief, reason why a physician is better paid than a carpenter; a lawyer than a policeman; a watchmaker than a ploughman; a shopman than a porter. It is true, that some operatives are well paid, whose work is neither hard to learn nor difficult to perform. Men, for instance who work at gunpowder-making, needle-grinding, and the like, usually obtain high wages, though their work requires but little knowledge or skill. But the high rate of wages in such instances forms only an apparent exception to the rule. The danger to life and health which such employments involve, prevents many from undertaking them; and the few who can be got to run the risk are entitled to high wages on the ground that their employment puts them to the cost, if not of superior knowledge and skill, yet of constant exposure to danger. Labour which is difficult to perform commands high wages, because the persons able to perform it are necessarily few in number; and labour which involves danger commands high wages, because few are willing to undertake it. The case of a successful operasinger, who sometimes earns a hundred pounds in a single night, may be adduced as an example of the effect in raising wages of both these causes combined. Very few are so highly gifted with vocal powers as to be able to be successful singers; and of those still fewer are willing to encounter the disparagement which usually attaches to those who appear on the stage. The ability to sing well being rare, and the willingness to sing on the stage still rarer-these two things combined serve to prevent competition, and to secure an apparently extravagant remuneration. But the rate of wages also differs even in the same trade. It is but seldom that all the operatives in the same workshop are paid alike. Usually, there are two or three rates of wages for what seems at first sight the same work; and those who receive the highest rate are always few in number, compared with those who receive the lowest. This difference is owing to the difference in the industrial ability or productive power of the workman. Workmen even of the same trade differ very materially in skill and diligence -some doing their work much more efficiently and quickly than others; and as it is the interest of the master to have his work always done in the best style and in the shortest possible time, he naturally keeps his eye on his workmen, and gives the highest wages to those of them who are most productive. The more productive any workman is, the more the master desires to have him and retain him. A thoroughly productive workman is seldom dismissed even when work is slack, and is always sure of the highest rate of wages current. And if to thorough industrial ability, he adds the moral qualities of sobriety, honesty, truthfulness, and conscientious fidelity, he is all but certain, not only to command constant employment and good wages, but to rise to some office or position of trust. Compiled. SONG OF THE SHIRT. "WORK! work! work! Till the brain begins to swim; Till the eyes are heavy and dim : Seam, and gusset, and band, Band, and gusset, and seam,Till over the buttons I fall asleep, And sew them on in a dream! "Work! work! work! My labour never flags: And what are its wages? A bed of strawA crust of bread and rags That shattered roof, and this naked floor A table-a broken chair And a wall so blank, my shadow I thank "Work! work! work! From weary chime to chime; Work! work! work! As prisoners work for crime! Band, and gusset, and seam, Seam, and gusset, and band, Till the heart is sick, and the brain benumbed As well as the weary hand. "Work! work! work! In the dull December light; And work! work! work! When the weather is warm and bright, While underneath the eaves The brooding swallows cling, As if to show me their sunny backs, "Oh! but to breathe the breath With the sky above my head, And the grass beneath my feet; For only one short hour To feel as I used to feel, Before I knew the woes of want, "Oh, but for one short hour,- A little weeping would ease my heart-- My tears must stop, for every drop With fingers weary and worn, In poverty, hunger, and dirt; And still with a voice of dolorous pitch- She sang this " Song of the Shirt!" HOOD. THE ATMOSPHERE. THE earth is surrounded by an ocean of gaseous matter, which extends upward from the surface of the land and water to a height of at least forty-five miles. This gaseous envelope is called the atmosphere, and the aggregate gases are called air. All gases are in a high degree elastic,—that is, they possess the power of increasing or diminishing in bulk according as they are less or more compressed. A volume of air which under ordinary circumstances occupies the bulk of a cubic inch, may be made, by the removal of the pressure, to expand so as to fill a whole room, while a renewal of the former pressure will reduce it to its former bulk. Nay, so expansive is air, that the smallest portion of it introduced into a large exhausted vessel becomes equally diffused through the whole space, and fills the vessel. Gravity being, so far as is known, common to all matter, it is natural to expect that gases, being material substances, should be acted upon by the earth's attraction, as well as solids and liquids. This is really the case, and the result is the weight or pressure of the atmosphere, which is nothing more than the effect of the attraction of the earth on the particles of air. It is the force of gravity that holds the atmosphere swathed round the earth. Were this force withdrawn, the atmosphere, owing to its elasticity, would be diffused and dissipated throughout space. The gravity or weight of the atmosphere is so great, that a man of middling stature is computed to sustain, when the air is heaviest, a weight of about fifteen tons. This weight would be insupportable were it not for the equality of the pressure on every part of the body; but, when thus diffused, we can bear even a much greater weight, as, for instance, in bathing, when we support the pressure of the water in addition to that of the atmosphere. Besides this, our bodies contain air, the spring of which counterbalances the weight of the external air, and renders us insensible to its pressure. The weight of the atmosphere, so far from being calculated to injure or incommode us, is in reality essential to our preservation; for, if it were removed, the air within us, meeting with no external pressure to restrain its elasticity, would distend our bodies, and burst the vessels that confine it. On the top of a high mountain, where the atmospheric pressure is much less than at the base, the traveller often bleeds at the nose and mouth, owing to the distension and bursting of blood vessels in these organs. It is found by experiment that the atmosphere presses on the earth with a force equal to about 15 lbs. on each square inch of surface, or, in other words, that a column of air, one square inch in base, and equal in height to the atmosphere, weighs about 15 lbs. But, owing to difference of temperature and other causes, this pressure varies slightly at different places, and even at the same place at different times. A well-known instrument, called a Barometer or Weatherglass, enables us to ascertain and measure both this pressure and its variations. The construction of the barometer is extremely simple. You fill with mercury a glass tube, about three feet in length and closed at one end; then, stopping the open end with your finger, you immerse it in a cup containing mercury. Instead of all the fluid which is in the tube running down into the cup, you will find that only part of it does so, the remainder continuing in the |