The Canadian pole system, which is largely in use in oil-field operations, is, like the first-mentioned method of drilling, of the percussion type, the chief essential difference being that, instead of a cable connecting the tools to the surface, poles are used. In former times, these poles were of ash-wood, but with the extended use of the system, iron rods took their place. The introduction of these iron rods was a distinct advantage, for they could be welded to whatever lengths are required, whereas the wooden poles, which were seldom more than 20 feet long, had to be spliced for practical work. The rig used with the Canadian system is not so powerful as that for the Pennsylvanian method, but the one great advantage of the Canadian system is that, for the drilling of shallow oil-wells, it could be operated by men of less experience. The success which has attended the operation of the pole system lies in the fact that although drilling by its means is very slow--for seldom is 250 feet per month exceeded--it is one of the best methods of drilling through complicated strata, and, in the hands of conscientious men, does highly satisfactory work. It might be of interest to very briefly refer to the operations of the system when a well is being drilled. The rig (that is, the superstructure above ground) is quite a simple framing, 70 or more feet high, with a base of about 20 feet. The power is usually derived from a steam engine, with the usual means for operating the gear from the derrick; fuel found locally, natural gas, or other form of heating agent used. One shaft and two spools running in bearings transmit the various motions desired, the drive being taken up by a pulley attached to the main shaft. On this shaft are keyed two band pulleys, which communicate by belting with two spools running immediately overhead in the upper part of the framework. Fastened to one extremity of the main shaft is a disc crank, which, through the medium of a connecting rod, transmits an oscillating movement to an overhead pivoted walking beam. In all systems of percussion drilling, the drilling bit is raised and then dropped a distance of several feet, the result being that the strata to be drilled are steadily pounded away. As the ground is pulverized by the percussion tools, the debris has to be cleared away so as to enable the drill to fall freely and to deliver clean blows to the unbroken strata, and this work is performed by appliances known as bailers and sand pumps. There is no need for me to go into the numerous technical details regarding this or any other system of drilling, for my only desire is to give a general impression as to the usual methods adopted for the winning of petroleum.