numerous tubes through which water is passing and thus this water is converted into steam. After passing these tubes the heated flue gases brought to life by the burning of the oil with the entering air are then conducted through the chimney out into the atmosphere. An interesting detail in the boiler plant is the automatic system of firing employed to minimize labor and improve efficiency in burning the oil. The Moore patent fuel oil regulating system which, from one central point, controls the oil supply, the atomizing steam and the amount of air to each furnace, is an interesting example. G H FIG. 9.-Moore steam to burner regulator. This regulator is actuated by the pressure from the main steam header so that any variation in steam requirements will cause a corresponding change in the amount of oil fired, due to an increase or decrease in the steam supply to the oil pumps and atomizers. Any fluctuation in steam pressure operates a governor whose power arm controls a bleeder valve on the oil pump discharge line, thus cutting off the oil supply if the steam pressure is too high and increasing it if too low. Any change in pressure in the oil main, in turn, controls the amount of steam for atomizing and of air for burning the oil. It is found that a simple straight line relationship exists between the amount of steam required for atomizing the oil and the amount of oil burned. Two diaphragms are employed to balance the pressures in the oil main and in the steam main connected to the burners. Any difference in oil pressure operates a rotary chronometer valve in the steam main through the medium of a fulcrum, water motor and lever connecting rod. Likewise the variance in oil pressure actuates a counterweighted rock shaft which moves the dampers so as to vary the amount of air admitted for combustion. GENERAL SUMMARY Thus it is seen in this brief description that by using crude oil as fuel three main cycles of operation are synchronously carried on in the modern power plant. Briefly summarizing, these are as follows: Water is taken through the boiler, converted into steam and passed through a driving mechanism, after which the steam is reconverted into water and this water again passed through the boiler. Simultaneously with this action water is being pumped through the circulating system to bring about the conversion of the steam from the power unit into water. Again oil in a finely atomized or gaseous state is being fed through pipes into the furnace, where it immediately combines with the proper quantity of oxygen from the entering air, and thus sufficient heat is liberated from the oil to evaporate the water supply of the boiler into steam for power generation. CHAPTER II FUNDAMENTAL LAWS INVOLVED IN STEAM ENGINEERING FIG. 10.-Mechanical energy in reciprocating units at Redondo. N the awful throes of the French Revolution and the immediate years following, the old saying that "every cloud has its silver lining" proved true in certain lines of scientific advancement, for the metric system of units was conceived and put into practice at that period. Our modern system of Arabic numerals, now practically universally adopted throughout the civilized world, required over five hundred years of human fumbling and competition with the old Roman method of numerical representation, before a complete replacement was accomplished, so intensely are we all creatures of habit and slaves to tradition. And so it is that although a period of a century is now passed since the institution of the metric system, modern central station engineering practice is still entangled with Fahrenheit scales, boiler horsepowers, mechanical horsepowers, myriawatts, Baume scale readings for gravity, inches of mercury vacuum, pounds pressure per sq. in., feet and inches-all units related so unscientifically and empirically as to cause bewilderment in itself. In the following discussion, however, the authors will endeavor to set forth the various units of expression in such simple language that it is hoped that even the beginner may have little difficulty in understanding their meaning. Let us first get some conception of the need for units of measurement and how such units are fundamentally conceived. Newton's Laws of Motion.-Fable has it that Sir Isaac Newton, when a boy in England lying one day under an apple tree and gazing upward, saw an apple fall to the ground. The contemplation of this phenomenon led Newton to give to the world three fundamental laws upon which modern engineering science is built. Briefly these laws are as follows: Law 1. Every body continues in a state of rest or a state of uniform motion in a straight line except in so far as it may be compelled by force to change that state. Law 2. Change of motion is proportional to impressed force and takes place in the direction of the straight line in which the force acts. Law 3. To every action there is always an equal and contrary reaction; or the mutual actions of any two bodies are always equal and oppositely directed. Hence a force is said to be acting according to Law 1 whenever the physical conditions are such that velocity is changed in magnitude or direction. Thus, when a train of cars is started or stopped, a force is necessary to cause this phenomenon, and this is evidently a change in the magnitude of the velocity. On the other hand, in the rotation of a fly wheel, the velocity may change solely in direction without a change in magnitude, and yet a force be necessary to maintain its parts in equilibrium. Hence a force may be considered as a push or a pull acting upon a definite portion of a body, but this tendency may be counteracted in whole or in part by the action of other forces. In the latter instance the force is usually denoted as pressure, and it is the consideration of this latter case, or the consideration of pressures, that will largely concern our attention in the generation of steam in a boiler. Three Fundamental Units of Length, Mass and Time.—In considering Law 2, it is seen that there is some inherent property in matter that makes it difficult to set it in motion. Physicists have defined this quality of matter as being the inertia of a body. Inertia is expressed quantitatively in engineering practice in terms of its mass, which is measured in pounds. In order that these quantities, force and mass, now introduced may be quantitatively measured, it is necessary to have some fundamental units upon which to base our computations. Three units only are fundamentally required; namely, a unit of length, a unit of mass, and a unit of time. Scientific practice has deduced for these units the centimeter, the gram, and the second, which are |