TWO:"Ach, but I have no case, I am not what you call a patient. It is another matter--a matter of sentiment."The sudden and varied resistance to line shafts tends to loosen couplings, destroy gearing, and produce sudden strains that are unknown in other cases; and shafting arranged with the usual proportions for transmitting power will soon fail if applied to driving trip-hammers. Rigid connections or metal attachments ace impracticable, and a slipping belt arranged so as to have the tension varied at will is the usual and almost the only successful means of transmitting power to hammers. The motion of trip-hammers is a curious problem; a head and die weighing, together with the irons for attaching them, one hundred pounds, will, with a helve eight feet long, strike from two to three hundred blows a minute. This speed exceeds anything that could be attained by a direct reciprocal motion given to the hammer-head by a crank, and far exceeds any rate of speed that would be assumed from theoretical inference. The hammer-helve being of wood, is elastic, and acts like a vibrating spring, its vibrations keeping in unison with the speed of the tripping points. The whole machine, in fact, must be constructed upon a principle of elasticity throughout, and in this regard stands as an exception to almost every other known machine. The framing for supporting the trunnions, which one without experience would suppose should be very rigid and solid, is found to answer best when composed of timber, and still better when this timber is laid up in a manner that allows the structure to spring and [107] yield. Starting at the dies, and following back through the details of a trip-hammer to the driving power, the apprentice may note how many parts contribute to this principle of elasticity: Firstthe wooden helve, both in front of and behind the trunnion; nextthe trunnion bar, which is usually a flat section mounted on pivot points; thirdthe elasticity of the framing called the 'husk,' and finally the frictional belt. This will convey an idea of the elasticity required in connecting the hammer-head with the driving power, a matter to be borne in mind, as it will be again referred to.
THREE:The Countess bowed; not for an instant did she change colour.Besides the attentions lavished on every wealthy individual, those who had no children were especially courted, and that too by others who were as well off as themselves with the object of being remembered in their wills. So advantageous a position, indeed, did these orbi, as they were called, occupy, that among the higher classes there was extreme unwillingness to marry; although, as an encouragement to population, the father of three children enjoyed several substantial privileges. This circumstance, again, by preventing the perpetuation of wealthy families, and allowing their property to pass into the hands of degraded fortune-hunters, rendered impossible the consolidation of a new aristocracy which might have reorganised the traditions of liberal culture, and formed an effectual barrier against the downward pressure of despotism on the one side and the inroads of popular superstition on the other.
TWO:
