The technical man will be interested in an outline printed in the _Iron Age_, which said: “Induced interior transverse fissures in basic open-hearth rails are due in part to an occasional hot rail being cooled so rapidly by the rolls or so chilled by the gusts of air before recalescence on the hot beds as to cause a log of some of the transformations of the metal in the interior of the rail head. Induced interior transverse fissures can only develop in the track from the effects of preceding causes, either of which is no longer a mystery.” The report of the railroad experts also laid stress on the theory that “gagging” rails--subjecting them to blows for the purpose of straightening them--was also likely to cause faults by injuring the metal. How does a “Master Clock” Control Others by Electricity? With the aid of electric currents, one clock can be made to control other clocks, so as to make them keep accurate time. By means of this method one high-class clock, usually in an astronomical observatory, compels a number of other clocks at considerable distances to keep time with it. The clocks thus controlled ought to be so regulated that if left to themselves they would always gain a little, but not more than a few minutes per day. The pendulum of the controlling clock, in swinging to either side, makes a brief contact, which completes the circuit of a galvanic battery, and thus sends a current to the controlled clock. The currents pass through a coil in the bob of the pendulum of the controlled clock, and the action between these currents and a pair of fixed magnets urges the pendulum to one side and to the other alternately. The effect is that, though the controlled clock may permanently continue to be a fraction of a second in advance of the controlling clock, it can never be so much as half a second in advance. An electrically controlled clock usually contains a small magnetic needle, which shows from which direction the currents are coming. The arrangements are usually such that at every sixtieth second no current is sent, and the needle stands still. Any small error is thus at once detected. The Story of the Calculating Machine How did Men Learn to Count? Historians tell us that man was able to count long before he was able to write. Of course, he could not count very far, but it was enough for his needs at that time. He had no money and very few possessions of any kind, so that he did not have much occasion to use arithmetic. It was fairly simple for prehistoric men to distinguish one from two, and to distinguish a few from a great number, but it was more difficult for him to learn to think of a definite number of objects between these extremes. Those who have studied the evolution of figures say that man found it hard to think of a number of objects without using a mark or a finger or something to stand for each object. That is how the first method of counting came into use.