Sonic idea of the nature of the machine may be collect ed from these drawings. With regard to the ex pence of the construction, the writer intended to conclude this description with an estimate; but upon reflection he has been induced to postpone this, at least for the present, for the following reasons.
1st, For two very conclusive and unavoidable reasons; the first trial of every mechanical experiment is conduct ed at a much greater expellee than what becomes neces sary in a more advanced stage. It is hardly to be expect ed that any projector, however conversant he may be both with the theory and practice of mechanics, can at once arrange and mature a complicated and extensive body of machinery, so as both to give it the greatest pos sible efficiency, and construct it with the strictest atten tion to simplicity and economy. It is perhaps as much as ever has been effected in new machinery, if the advan tage gained by its adoption be sufficient to counterba lance the difficulties to which it is exposed, and leave an ultimate profit in its favour. Hence projectors very fre qu,ntly, from forming expectations more sanguine than reason will warrant, are apt to involve both themselves and others in disappointments, the more severe in pro portion to the expectations which have been excited. But
the engineer capable of even much greater preci sion in all the minutix of his plan than is generally found to be the case, it would still be impossible that he could conduct his first experiments upon terms nearly equal to those which may be obtained afterwards. Every operative mechanic whom he may have occasion to em ploy, must have a considerable practice before he can execute his work either so perfectly or so speedily as ,in matured businesses. It is also impossible to allot or ap portion the various departments of the work in that order and method necessary to produce that division of labour which is the very essence of every business. Upon the whole, perhaps the most economical plan is merely to try the experiment upon a very limited scale for some time, and thus to purchase that experience which must be purchased at as small an expellee as possible. (J. D.)