This section is from the book "Amateur Work Magazine Vol6". Also available from Amazon: Amateur Work.
Given two young men of equal ability, and let both of them go through good technical schools, both graduating as chemists, or as mining, mechanical, civil or electrical engineers. The one during the course of his study has covered much ground, has stored his mind with facts, has learned carefully and well the methods and manipulation required in the branch chosen. The other has not covered so much ground, but every bit of information that he has he thoroughly understands; he has acquired principles rather than a large array of facts, and he knows the reasons why. Let now these two begin work after graduation in the same place, and we are ready to confess that the former will make the best showing, and progress the more rapidly for the first year or two, but if our observation is worth anything, the latter will distance his competitor at the end of ten years.-Dr. Chas. B. Dudley.
The transporting power of a current of water, or the weight of the largest fragment it can carry, varies as the sixth power of the velocity. That is, if a current of certain velocity will move a cubic inch of stone, when the velocity of the current is doubled, it will move a stone sixty-four times as large, and if the velocity were increased ten times, the transferring power would be increased 1.000.000 times.
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The fact that a luminous emanation of variable shape will appear in the dark at such points on the surface o: the earth below which there are extensive ore deposits at a more or less considerable depth was recorded in Germany as far bacK as 174/, says the "English Mechanic" Immediately before or during a thunder-storm these phenomena are said to be especially striking. Similar observations have more recently been made in North America in the neighbourhood of ore deposits. Though much should be ascribed to superstition and to errors of observation, the fact has nevertheless been confirmed by recent investigation. The electric emanation given off from the surafce of the earth has, in fact, been repeatedly ascertained photographically by Mr. K. Zenger. Plates coated with fluorescent substances were used. It may thus be taken for granted that the emanations in question occur win an especially high intensity at those points of the ground where good conductors of electricity are found in large amounts in the neighborhood of the surface of the earth; in other words, above ore deposits, which are very good conductors of the electric current. Lignite and coal, especially when containing pyrites, are fairly good conductors. The difference in the intensity of radiation as compared with points free from any ore would seem to be recognized by means of photography, thus affording to geologists a rather simple means of locating ore and even coal deposites.
Generally speaking, electric furnaces may be divided under two main headings-namely: those in which the heating effect is produced by the electric arc established between two carbon or other electrodes con-nected with the source of current, commonly known as arc furnaces; and those in which the heating effect is produced by the passage of the current through a resistance, which either forms part of the furnace proper, or is constituted, by a suitable conducting train, of material to be treated in the furnace. The principle of the later type is analogous to that involved in the heating to incandescence of the ordinary electric lamp filament, and such furnaces, are as a class, known as resistance furnaces.