L. MECHANICS AND ENGINEERING. 473 



fessor Siemens, as lately published in Dingler's Polytechnic 

 Journal, and warmly recommended for the propulsion of sew- 

 ing-machines and other forms of the lesser industries. The 

 motion of the machine commences directly with the action 

 of the steam, and the steam-generator itself rotates. 18-4, 

 September 5, 1873, 624. 



hock's petroleum motor. 



In the imperial printing-office at Vienna, three presses, of a 

 capacity of 1200 sheets per hour, are driven by a motor in- 

 vented by Hock, which promises to be very useful for small 

 industrial establishments. Combustion of petroleum in the 

 working cylinder, and the heat developed by it, constitute 

 the motive power. The machine is said to be very regular 

 in action, to be entirely free from danger, to require little at- 

 tention, to occupy little space, and to be very economical in 

 running, \\ pounds of petroleum per hour being reckoned for 

 one horse-power. Like the gas-engine, it is also ready at 

 all times, and it is easily cooled down. 14 C, CCXIL, 73. 



TRIAL OP THE AMERICAN COAL-CUTTING MACHINE. 



The first practical trial of an American coal-cutting ma- 

 chine was recently made at the Coal Brook mines of Messrs. 

 Niblack, Zimmermann, & Alexander, a few miles from Brazil, 

 Indiana. 



The machine in question is known as Brown's Monitor 

 Coal-cutter, and consists, according to the description given 

 of it, of a five-horse-power steam-engine, driven by steam 

 that is carried into the mine by a steam-pipe, terminating in 

 a flexible hose of rubber, so as to permit freedom of motion 

 in the machine. It is intended to substitute compressed air 

 for steam upon the termination of the experimental trials. 

 The cutting arrangement is an iron rim of four feet in diam- 

 eter, which has on its periphery movable steel teeth placed 

 at points twelve inches apart. These teeth may be taken 

 out and ground whenever they become dull. The construc- 

 tion and operation of the cutter is such that it can be inserted 

 to a depth of three and a third feet, or seven eighths of its 

 whole diameter. The machine runs on a movable track, and 

 is fed by a screw movement. The track is laid along the 

 side of the coal at the proper distance from it, and when a 



