ONE:(1.) Why have belts been found better than shafts for transmitting power through long distances?(2.) What are the conditions which limit the speed of belts?(3.) Why cannot belts be employed to communicate positive movement?(4.) Would a common belt transmit motion positively, if there were no slip on the pulleys?(5.) Name some of the circumstances to be considered in comparing belts with gearing or shafts as a means of transmitting power.Another principle in planing machines which deserves notice is the manner of driving carriages or platens; this is usually performed by means of spur wheels and a rack. A rack movement is smooth enough, and effective enough so far as a mechanical connection between the driving gearing and a platen, but there is a difficulty met with from the torsion and elasticity of cross-shafts and a train of reducing gearing. In all other machines for metal cutting, it has been a studied object to have the supports for both the tools and the material as rigid as possible; but in the common type of planing machines, such as have rack and pinion movement, there is a controversion of this principle, inasmuch as a train of wheels and several cross-shafts constitute a very effective spring between the driving power and the point of cutting, a matter that is easily proved by planing across the teeth of a rack, or the threads of a screw, on a machine arranged with spur wheels and the ordinary reducing gearing. It is true the inertia of a platen is interposed and in a measure overcomes this elasticity, but in no degree that amounts to a remedy.
THREE:A cry rose to her lips, but she stifled it. In a sudden, blind, unreasoning fear she fled noiselessly up the stairs. She had seen that man's features. It was the face of the man from the Corner House!
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