Page:The Kinematics of Machinery.djvu/422

 400 KINEMATICS OF MACHINERY.

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Review of the preceding Results.

Chamber-crank gear occurs in such an immense variety of forms that our investigation of it has necessarily been somewhat extended. Even now I cannot for a moment say that I have exhausted all the forms in which it has appeared. J may rather say with Uhland's knight :

" Wer such en will im wilden Tann, Manch' Waffenstiick nocli fiuden kann, 1st mir zuviel gewesen."

A comparison of the machines described shows indeed that there are many easily-constructed inversions of existing mechanisms which have not yet been proposed, and many analogies to existing forms which have not yet been tried : so we may look forward still to the production of whole series of new chamber-crank trains by the never resting empirics.

What our analysis has done for us is by no means unimportant. It has led us in the first place to those general laws which inventors and improvers alike have followed unconsciously and unsuspectingly. The reason for their having so unanimously chosen a crank- train as the foundation for their work must be left for examination in a later chapter. Meantime we have been able to reduce to order and principle the confusion which existed in the material already ac- cumulated. Our arrangement has not been chosen arbitrarily, but has developed itself from the essential nature of the machines ; on this account it is available also for future forms of the same class of machines, which indeed we have now the means of scien- tifically designing. 52 At the same time the principles which we have found furnish us with the means of forming a distinct opinion as to the value of the machines individually. A few out of the whole number show themselves to be practically useful ; the majority, however, are not suited for their proposed purpose, or at best are distinctly inferior to others as practical solutions of the problem. The complete delusiveness of the supposed advantages of many