CHAPTER I. Introduction (Part 3)

is at present. To attain that standard opportimities at school must be diligently grasped, apprenticeship under a practical master should be steadily served, and during apprenticeship three or four evenings a week should be given to attendance at classes in technical schools for the study of mathematics, drawing, practical geometry, plumb- ing and metal-plate work, mechanical engineering, building construction, steam, heat, hydrostatics, hydraulics, aerometry, and any other subjects available bearing on the plumber's trade. Examinations should be passed and certificates THE EDUCATION OF PLUMBERS. 21 obtained in these subjects, which will fully occupy the evenings of the seven years' apprenticeship. Such a preparation for a trade may appear to some too arduous; but it will bring a full reward, not only by the conscious power which skill and knowledge give, but also by success and prosperity in life. CHAPTEE III. ELEMENTARY SCIENCE FOR PLUMBERS. For practical teaching purposes the author prefers once for all to explain in this chapter the elementary natural science which plumbers specially require to know rather than to drag in frequent explanations of phenomena here and there through future chapters. Practical plumbing rests upon the foundation of natural science ; therefore it is as important for plumbers to attain a grasp or comprehension of the science underlying their craft as it is important for them to know how to handle their tools. Without possession of a fair elementary know- ledge of this science, workmen have no true claim to the title of plumbers. Mere handicraft skill is insufficient. Science is a name which frightens working men, because they have never been made acquainted with its simplicity, beauty, and usefulness. Science is knowledge ; it is truth ascertained, defined, and determined accurately. Scientific research is a seeking after truth for its own sake. There is nothing in science to object to ; but, on the contrary, everything for the humblest artisan to desire and to seek after earnestly. Science is of the utmost practical importance to every plumber. We can never properly acquire for ourselves, nor communicate to others, accurate technical knowledge in any trade, unless we have gained some actual acquaintance with the natural forces and laws underlying and connected with that trade. 22 ELEMENTARY SCIENCE FOR PLUMBERS 23 Every plumber and every teacher of plumbing should seek diligently and earnestly for this knowledge. The more we learn the better shall we be fitted for our work, and the easier and pleasanter shall knowledge become. Popular education in physics, or the knowledge of nature, has been so n^lected that very few otherwise well-educated people are prepared to explain, or even to understand, the causes of the most simple practical phenomena occurring daily within their observation. A banker ignorant of arithmetic and book-keeping, or a doctor without a knowledge of anatcony and medicine, would be very likely to fail in his profession, and to do serious injury both to himself and to others. The world is now learning that, unless a manufacturer understands the science governing the processes of his manufacture, he is not to be depended upon for the best work, and therefore the world is looking for plumbers and for technical teachers of plumbing who make it their aim to know their business thoroughly. Knowledge of the forces of nature is more essential for plumbers than for the artisans of many other trades. Let us first think in a broad general way of our subject. Energy and matter are the two great realities of the universe. We are surrounded by them; we observe and can study their properties, and may use them to our advantage when we have learned the way to do so. We can direct, control, concentrate, store, and utilise both energy and matter, but we can neither create nor destroy; they are immutable and indestructible, fixed quantities, definite existing realities. Yet no man by his own searching has found out where they originally came from, or what they definitely consist of. We know something of their properties, and it is with their properties and effects we have to do as practical men. Physics is the study of the energy which acts upon the 24 DOMESTIC SANITARY DRAINAGE AND PLUMBING. matter compoBing the universe, and it is or should be of intense interest to the technical teacher of plumbing, and to every one of his pupils. Energy is the power of doing work, and, when applied as force, it changes the state of a body from rest into motion, or from motion into rest. Energy is of two kinds— energy of motion and of position. The actual energy of motion acquired by a jet of water thrown, as against the attraction of gravitation, by any external i^ency to the top of a house, appears to become gradually absorbed as it ascends with gradually decreasing velocity. If that jet of water be caught and stored in a tank on the top of that house it exerts no longer the energy of motion ; but, though held at rest, it possesses, stored up, an energy of position exactly equal to the amount expended in sending it there ; it possesses a potential energy, which plumbers call a "head of water." Nearly all the energy in this world may be traced to the sun ; but that luminary must have received its energy from some great power in order to distribute it to us, and, unless the sun is being replenished, the day will come when he himself shall be no more — ^his energy not destroyed, but transferred to other stores. It is the sun's energy that warms the air, causing the winds to blow ; evaporates the waters of the ocean, form- ing the clouds and the rain; dispenses heat and light, causing the plants to grow and timber to form; reacting by chemical processes, and converting them into stores of coaL We are now excavating from coal mines, peat fields, and oil wells the energetic sunshine of past ages, redeveloping the energy of power, by raising steam and employing it in various engines to do work once more. Study may be considered a mental energy of motion; ELEMENTARY SCIENCE FOR PLUMBERS. 25 while knowledge acquired and stored for use is clearly mental energy of position, ready to be utilised when required in brain work. When we work either with our brains or our hands we are using up energy; but it is neither lost nor destroyed. All work proceeds from energy, so the plumber who possesses most energy should get on best in his trade. Energy is the workman's capital: he requires a good share to commence business with, stored not only in his muscles, but also in his brain. We have heard that this energy proceeds from the sun ; but by what means ? Well, the heat and light causes food to grow ; the food is eaten, and by chemical processes, in which the sun takes part, it is transformed into flesh and blood, brain and muscle. A certain proportion of our breakfasts and dinners, accurately measured by scientific men, goes to pur muscles and our brains. There are a great many men who would always be ready and willing to store an immense amount of energy if it only depended on taking in breakfasts and dinners ! but as food requires digestion and assimilation to render it of use, so the muscles require practice and the brain study to develop and direct their powers. Thus the force or muscular energy which gives motion to or stops our tools, and the thought or brain energy which guides and regulates the manner of using them, depend not only on practice and study, but on the regular supply of food, which we know depends on the influences of the sun ; and if we would look further back we may reverently acknowledge our ultimate dependence on the power and beneficence of the Great Creator, in whom we are told that we live and move and have our being. Matter is the vehicle or carrier of energy. The vast 26 DOMESTIC SANITARY DRAINAGE AND PLUMBING. energy in the attraction of gravitation, the attraction of cohesion, and the attraction of chemical affinity cannot display its effects and powers without matter to act upon and through. Matter differs from energy in being essentially material. It possesses volume or extent, impenetrability or occupy- ing substance, inertia, indestructibility. These are inherent properties of matter, and are to be distinguished from its accidental properties, such as weight, smell, taste, etc., which depend on circumstances. It is not possible to form any conception or idea of matter without allowing that it possesses volume or extent ; the very smallest atom conceivable must have length, breadth, and thickness, and must therefore occupy or fill a definite space, however minute. Into this space no other atom can enter until the occupying atom has moved away. This is the simple meaning of extent or impenetrability. We may be assisted to realise the idea by comparing in our minds the minutest atom of matter which has length, breadth, and thickness, occupies space, and can even be weighed, with the point in geometry which has neither length, breadth, nor thickness, occupies no space, and can- not be weighed, and therefore is not matter or material, but something clearly definite for all that, marking accurately a precise position in space, and serving a useful purpose in science and art. Matter is stated to consist of simple elementary atoms which cannot be. hurt, destroyed, or divided. Philosophers have discovered sixty-four such elements, and many more may yet remain unknown. These combine in manifold ways, forming compound substances — chlorine and sodium forming salt; silicon and oxygen forming sand; oxygen and hydrogen forming water ; oxygen, nitrogen, and carbonic acid gas forming air. All solids, liquids, and gases are ELEMENTARY SCIENCE FOR PLUMBERS. 27 composed of these little atoms, or molecules, or particles of matter, and each substance is formed of definite and distinct particles, so small that our minds are unable to realise their extreme minuteness. Suppose we could subdivide one grain of salt, for instance, until we finally arrived at the smallest particle in which it could exist as salt This minute molecule of salt contains two distinct elements, chlorine and sodium, and is therefore capable of being further subdivided into the atoms of those elements, which when separated are no longer salt, but simple sodium and chlorine. If we can conceive the smallest particle visible to us in the most powerful microscope, measuring, say, the Trnnnnjtl^ part of one inch, that minute particle of matter contains many millions of its molecules. The realisation of such extreme minuteness is not easy to our minds. • These particles of matter, whether in a solid, liquid, or gaseous state, are, as already stated, in a condition of intensely rapid motion, though they seem to us to be at rest. The molecides or particles of solids, such as iron or lead, are confined by their surrounding molecules in a certain mean position, about which they vibrate in never-ceasing motion. The molecules of liquids and gases, such as water and air, are not so confined, but are free to diflfuse themselves throughout their mass in every possible direction, striking and jostling each other like a swarm of midges, every collision changing their direction of movement. The pressure of gases is considered to be produced by this marvellously rapid movement, so rapid that the atoms of hydrogen gas come into collision eighteen hundred million times in every second of time. Try for an instant to realise that statement. Steam, air, or gas confined in any closed vessel presses 28 DOMESTIC SANITARY DRAINAGE AND PLUMBING. against the sides with a pressure due to the number of collisions or impacts of the molecules against the sides. In a cubic inch of any gas — sewer gas, for instance — at a standard temperature and pressure, you have the same number of molecules of the gas. These strike the sides of the enclosing vessel, or drain, or soil-pipe, a certain number of times, producing a certain pressure. If you introduce by any means double the quantity of gas, say two cubic inches, you double the number of particles, and consequently you double the number of collisions and you increase the pressure. You may also increase the rapidity of the collisions and the consequent pressure without adding to the number of the particles of the gas confined in the vessel, drain, or pipe, by simply applying heat, which causes them to bombard the sides more rapidly, the pressure on the sides increasing as the squares of the velocities. Heat compels bodies to change their condition ; it pulls asunder the particles of ice, and we may observe that during the process of melting this heat has no effect on the mercury column of a thermometer placed in contact, which stands steady at the freezing point of 32^ F., the added heat being all expended in tearing the particles of ice asunder and changing the solid into liquid. If we continue to apply heat to the water thus formed the mercury column will rise until it arrives at the boiling point of 212** F., and there it wiU remain because the added heat is all expended in separating the particles of water into steam. The comparative dimensions of this one sub- stance under the three forms of solid ice, Uquid water, and gaseous steam, are 11 cubic inches ice = 10 cubic inches water = 1,650 cubic inches steam. For experiment fill a Ught zinc cylinder with steam, quickly seal it air-tight, and pour cold water on it; the steam is instantly condensed, and the cylinder collapses. If ELEMENTARY SCIENCE FOR PLUMBERS. 29 a strong vessel containing ten cubic inches of water be subjected to the action of frost the water at the instant of freezing into ice will burst the vessel, because there is not space for the additional cubic inch which that ice occupies. This expansion of water at freezing point to the extent of one inch in every ten inches is the cause of the bursting of exposed lead pipes during winter time. When matter thus expands it becomes lighter bulk for bulk; therefore, when ten inches of water become eleven inches of ice, each inch of ice is lighter than each inch of water. Ice, therefore, floats on water. If, on the contrary, it became heavier and sank, it is obvious that lakes and oceans would in time become solid ice. Ice at the bottom of the ocean would escape the melting heat of the sun, and year by year freshly formed ice would sink and rapidly accumulate. Matter possesses an inherent property called inertia. Newton's first law of motion may be thus stated. Matter at rest must remain at rest until some external force sets it in motion, and matter in motion must continue in motion in one straight line until some external force stops it or changes the direction or speed. Inertia may be simply illustrated by placing one pound of lead on a sheet of tin-plate ; suddenly withdrawing the tin-plate sideways the lead remains stationary until the sup- port is gone, when it is drawn to the ground by the force of gravity. The inherent inertia in the mass of lead matter prevents it following the tin in a sudden horizontal movement, no force acting to compel motion sideways. As we sit or stand we are being carried round on the surface of the earth at the rate of four hundred miles an hour ; at the equator men are carried round at the rate of a thousand miles an hour. If our bodies did not possess 30 DOMESTIC SANITARY DRAINAGE AND PLUMBING. inherent inertia the earth would pass under our feet at the rate specified when we jumped upwards. Inertia causes some of the molten lead in a plumber's solder-pot or ladle to be left behind if the pot is jerked suddenly from the fire. This resistance offered by matter is termed vis incrtice, or the force of inertia. The inertia of matter can be further illustrated by hanging three jars by a string side by side— one full of sand, one full of water, one full of air. Twist each round a hundred times. The solid sand will be the slowest to commence revolving, because of the inherent inertia of the sand re- quiring time to have the motion of the jar communicated to it, but once fairly started it will keep revolving the longest, also owing to the inertia of the solid sand. The water-jar will start revolving quicker, but will leave the liquid body of water behind, as the liquid allows the jar to slide round it, not instantly communicating its motion to the water; owing to inertia the water remains comparatively still, and acts like a check or brake by friction on the revolution of the jar, pulling it up and stopping its motion long before the sand- jar has ceased to revolve. The air-jar, not being acted on by any matter possessing so much inertia as sand or water, is simply affected by the lesser inertia of the gaseous air, and will commence to revolve quicker and to cease revolving quicker than either the sand-jar or the water-jar. Matter is indestructible. No known human power can destroy matter. You may compel it to change its appear- ance or to become invisible to our eyes, but the elements or molecules will still exist, capable of being brought back again to the condition you succeeded in altering them from. If, for instance, you take a piece of marble or chalk, into which carbonic acid had been absorbed and stored up millions of years i^o, and if you decompose the solid with ELEMENTARY SCIENCE FOR PLUMBERS. 31 hydrochloric acid, the same molecules of carbonic acid gas will be evolved, possessing the same properties, unchanged,