Issue 12 and Volume 49.

MODERN DRILLING MACHINES. In large undertakings such as railroad construction, canal building and excavating in stone and cement quarries, as well as in mine prospective and drilling of artesian wells, the modern drilling machine plays an important part. The accompanying illustration, Fig. 1, shows a portable type of drilling machine being transported across China to drill for gold. A great part of the 400 miles to be traveled was low and marshy and the machine had to be hauled by coolie convicts. Portable drilling machines are self-propelled except under the most difficult conditions. Where electric current is available they are operated by motors, while a double-cylinder opposed gasoline engine of 7 horsepower capacity, with a 5-inch bore and a 5-inch stroke, is used to do the work where liquid fuel can be utilized to advantage. Where it is necessary to use coal or wood as a fuel, a boiler and…

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