Page:Popular Science Monthly Volume 45.djvu/639

Rh comparatively short time. A traveling crane of this description, as most of our readers are aware, consists of a long carriage having a pair of rails on which runs the crane truck carrying the lifting machinery. The long carriage, which is supported a suitable height above the floor, stretches across the width of space to be commanded, and itself has a sideway movement on several supporting rails which run the length of the space to be operated over. Thus by a combination of the two movements the crane truck commands the whole floor.

During the work of assembling the penstocks, wheel cases, turbines, etc., at the wheel pit, a view of this great slot with its contents was wonderfully impressive in giving an idea of the vastness of the whole enterprise. The great depth of this long, narrow pit, which made it impossible to see to the bottom except with the assistance of lamps in the lower part, the mysterious-looking pipes (the penstocks) rising vertically, new sections being constantly added much in the same way that a stovepipe is put together, except for the permanence given by the heavy riveted seams, and the enormous power and flexibility of operation of the immense traveling crane which rapidly conveyed in every direction great masses of iron and steel obedient to the turn of a switch, made a combination of impressive effects not quickly forgotten.

To obtain an idea of just what the relation to each other of the various parts in the installation is, the reader is referred to the sketches numbered 6, 7, and 8.

It may be mentioned that, to withstand the very considerable hydraulic pressure at the lower part of the penstocks, these tubes are built of thicker and thicker plates from the top downward.

There has been very little criticism of the mechanical details of construction so far referred to; on the contrary, very little can be said except in praise of the fertility of resource and high general competence of the engineers who have had this work in hand. With regard, however, to the particular design of the generators from an electrical rather than a mechanical standpoint much and lavish criticism, if not condemnation, has appeared in various quarters. Whether the grounds for this criticism are well founded or not it would be presumptuous at this time to attempt to declare, but we may say that where, as in this case, one man has had practically the entire control of the design of the electrical apparatus, we may usually look for, rather than be surprised at, a great amount of setting up of individual opinion against the views which he may embody in practice, often a good deal irrespective of the probably cogent reasons which may have induced him to adopt the course in question.

Without attempting to decide between the various views which are plentifully to hand in criticism of certain electrical