6. The burning─out of a boiler, due to carelessness on the part of a watchman over night. 7. The non─arrival of necessary and important material. 8. Irregular blasting, due to irregular spacing of drill holes, or to bad loading, or to poor detonators or a poor exploding machine, or to irregularity in the character of the rock itself. 9. Erratic action on the part of one or more of the men, due to drunkenness, ill─temper, or general contrariness. 10. Errors on the part of foremen in coöperation, some of which are not detected in time to be eliminated. In working out any special problem, care should be taken that such accidental causes affecting performance──whether they decrease the performance or, as may happen, increase it──should be carefully noted and be a part of the regular report on the work. These features of a report ordinarily are ignored as being unimportant, but they are of the utmost value to the success of the work. STIMULATING THE MEN The art of persuading a man who is turning out 500,000 foot─pounds of work in ten hours, to turn out 800,000 foot─pounds of work in ten hours with a trivial increase in pay, is on its face difficult; but is by no means impossible, and a list of some of the ordinary means of doing this should not be out of place here. 1. =Watching the Work.= If, on the average work under the observation of a foreman whom they know, the men are made to realize that their individual performance is being watched and recorded by someone who is above and beyond their own foreman, there will usually result an increase in performance of from 10 to 20 per cent per man; and particularly if a tab is kept upon the performance of the gang as a whole, the foreman will add his own stimulus to that applied by the men themselves, resulting in highly increased efficiency. On such work as teaming, where teams are hauling earth along a road for a considerable distance, a punch─card is very valuable. The driver knows that the time of his trip is being recorded and compared with the time for the same work done by other drivers; and it has the effect of concentrating his mind upon his performance, which in itself causes him to use more care in cutting down delays and keeping his team up to their work. In the operation of drilling, most valuable results have been achieved by giving each drill runner a card on which, at the completion of each hole, the time of the finishing of the hole is punched; and also the time of starting the new hole, in the same way. This card will then show the length of time that it took to drill the hole, and the length of time required to move his drill. He will be stimulated to move quickly, which in soft rock is an exceedingly important element of the drilling work, and he will be stimulated in the effort to get his holes down rapidly.