By the aid of our improved machine tools, cylinders can now be bored with such perfect accuracy, and the pistons be fitted to them with such absolute exactness, that the small quantity of water which the steam always deposits on the upper side of the piston, not only serves as a frictionless packing, but also serves as a lubricant of the most appropriate kind. I have applied the same kind of piston to ordinary water-pumps, with similar excellent results. In most cases of right packed pistons we spend a shilling -- to save sixpence -- a not unfrequent result of "so-called" refined improvements.

An instantaneous Mode of producing graceful Curves, suitable for designing Vases and other graceful objects in Pottery and Glass.

The mode referred to consists in giving a rapid "switch" motion to a pencil upon a piece of paper, or a cardboard, or a smooth metal plate; and then cutting out the curve so produced, and employing it as a pattern or "template," to enable copies to be traced from it. When placed at equal distances, and at equal angles on each side of a central line, so as to secure perfect symmetry of form according to the nature of the required design, the beauty of these "instantaneous" curves, as I term them, arises from the entire absence of any sudden variation in their course. This is due to the momentum of the hand when "switching" the pencil at a high velocity over the paper. By such simple means was the beautiful curve produced, which is given on the following page. It was produced "in a twinkling," if I may use the term to express the rapidity with which it was "switched." The chief source of the gracefulness of these curves consists in the almost imperceptible manner in which they pass in their course from one degree of curvature into another. I have had the pleasure of showing this simple mode of producing graceful curves to several potters, who have turned the idea to good account. The illustrative figures on the next page have all been drawn from "templates" whose curves were "switched" in the manner of Fig. A.

A Machine for planing the smaller or detail parts of Machinery, whether Flat or Cylindrical.

Although the introduction of the planing machine into the workshops of mechanical engineers yielded results of the highest importance in perfecting and economising the production of machinery generally, yet, as the employment of these valuable machine tools was chiefly intended to assist in the execution of the larger parts of machine manufacture, a very considerable proportion of the detail parts still continued to be executed by hand labour, in which the chisel and the file were the chief instruments employed. The results were consequently very unsatisfactory, both as regards inaccuracy and costliness.

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• With the desire of rendering the valuable services of the Planing Machine applicable to the smallest detail parts of machine manufacture, I designed a simple and compact modification of it, such as should enable any attentive lad to execute all the detail parts of the machines in so unerring and perfect a manner as not only to rival the hand work of the most skilful mechanic, but also at such a reduced cost as to place the most active hand workman far into the background. The contrivance I refer to is usually known as "Nasmyth's Steam Arm." None but those who have had ample opportunities of watching the process of executing the detail parts of machines, can form a correct idea of the great amount of time that is practically wasted and unproductive, even when highly-skilled and careful workmen are employed. They have so frequently to stop working, in order to examine the work in hand, to use the straight edge, the square, or the calipers, to ascertain whether they are "working correctly." During that interval, the work is making no progress: and the loss of time on this account is not less than one-sixth of the working hours, and sometimes much more; though all this lost time is fully paid for in wages.

Apparatus for enabling the machine to execute segmented work

But by the employment of such a machine as I describe, even when placed under the superintendence of well-selected intelligent lads, in whom the faculty of good sight and nicety of handling is naturally in