Professional Papers by the Corps of Royal Engineers ... Royal Engineers Institute: Occasional papers, Volume 18

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Page 6 - But, admitting that there is a particular temperature at which a metal becomes pasty, its range is so limited in the case of the common metals, that it would scarcely be possible to hit upon it with any certainty in practice ; or, if it were possible, its duration would be too short for the performance of the necessary manipulations in welding.
Page 6 - Iron has one remarkable and very important property, namely, that of continuing soft and more or less pasty through a considerable range of temperature below its melting point. It is sufficiently soft at a bright...
Page 6 - ... Iron has one remarkable and very important property, namely, that of continuing soft and more or less pasty through a considerable range of temperature below its melting point. It is sufficiently soft at a bright-red heat to admit of being forged with facility, as every one knows ; and at about a white heat it is so pasty that when two pieces at this temperature are pressed together they unite intimately and firmly. This is what occurs in the common process of welding. Generally, metals seem...
Page 71 - I represents the current as a function of the time. Suppose there is no other coil wound over the core, then the ordinates of the curve represent to a suitable scale also the exciting power on the core, and it is obvious that the magnetization of the core, or, to speak correctly, the total induction passing through it, will change more or less in accordance with the curve I. If the permeability were constant, the induction would be strictly proportional to the exciting power, and by the selection...
Page 94 - ... long distances are beginning to turn their attention to some forms of alternator as the most certain means of solving such problems. I shall have something more to say on this subject in the third lecture. For the present I must limit my remarks to the machines as required for lighting. 6 CHAPTER VI. DESCRIPTION OF SOME ALTERNATORS. In the limited time at my disposal it would be impossible for me to give you anything like an exhaustive account of the various machines now in use. I shall therefore...
Page 77 - ... through the wire is proportional to the volts, the rate at which heat is developed is proportional to the square of the instantaneous volts, that is, to Oe squared in Fig. 10, if by OE we represent the maximum volts. Now, to find the general effect of a large number of succeeding instantaneous voltages on the voltmeter, we have to draw .the projections O, of OE for a large number of positions. Let us take these positions in pairs, such as OE and OE', with an Fig.
Page 203 - ... doing work is by means of its pressure, but the difference between this method and the preceding method is more ap-parent than real. The so-called pressure of water is the result of weight or its equivalent. For practical purposes it may, nevertheless, be said that there are three ways in which water power can be applied to the performance of work: (1) As kinetic energy, or through the velocity of the fluid; (2) by weight: and (3) by pressure. Each of these three methods requires a different...
Page 63 - ... direction, or whether both electricities flow simultaneously in opposite directions, or whether there is any transfer of electricity through the wire at all. Indeed, according to modern views, there is merely transfer of energy, but not through the wire, the transfer taking place throughout the space surrounding the wire. To talk about an electric current flowing through a wire may therefore be an unscientific way of expressing our meaning, but it is a very convenient way, and, therefore, generally...
Page 103 - ... In all these the copper loss is 2 per cent. The hysteresis loss is given in each case. You can see at a glance what a great difference there is in the amount of copper required, and how by a skilful choice of the proportions the cost of the apparatus can be reduced without lowering its efficiency. Before concluding this part of my subject, I wish to draw your attention to the relation existing between the linear dimensions of a transformer and its out-put and hysteresis loss. Imagine that after...
Page 205 - ... water may flow inward from the circumference to the centre or outward from the centre toward the circumference. The best-known type of the inward flow is the Francis turbine, and of the outward flow the Fourneyron turbine. The Axial Turbine, or parallel flow as it is sometimes called, is one in which the water flows through in a direction generally parallel with the axis of rotation. The water may flow from the top downward or from the bottom upward. The best known type of the downward flow is...

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