There is, however, a more decided difference between West's system and those previously in use, for it is marked by the fact that the slabs composing the shell of the whole structure in many cases may be built up before the filling-in is deposited between the slabs, and in none of the other cases can this be done. In fact, only in the first two cases before mentioned can more than one course of slabs be laid before filling-in of some kind must be done. Compared with the ordinary method of building in concrete, this system avoids: 1. The charge for use and waste of wood casings; 2. finishing the face of the work (both inside and outside) after the structure is raised, and, therefore, the bursting-off of the finished face; and 3. the difficulties encountered in working mouldings and other ornaments on the face of the work by the ordinary plasterer's methods. It also provides a face of any of the usual colors that may be obtained in concrete, besides a facing of any other material, such as marble, etc., and produces better and more durable work, at the same time showing a saving in cost, especially in the better classes of work; all of which is effected with less plant than ordinarily required.
For engineering work, such as sea walls, the hexagonal slabs, made of greater thickness than those employed for ordinary walling, will answer admirably, especially if the grooves be made proportionately larger. By the use of these slabs the work may be built up with great rapidity. For small domestic work, such as the dwellings of artisans, these slabs; which are of such a form as to render them easy of transport, may be supplied to the workmen themselves in order that they may erect their own dwellings, as, on account of the simplicity of this system and the absence of need of plant, any intelligent mechanic can do the work.
Any arrangement of independent scaffolding may be employed for this system, but that invented specially for the purpose by Mr. Frank West, as shown in Fig. 26 of our engravings, is to be preferred. It not only supplies the necessary scaffold, but also the necessary arrangements for hoisting the slabs, as well as for raising the liquid concrete and depositing it behind the slabs. It is really an independent scaffold, and may be used wherever a light tramway of contractor's rails can be laid, which in crowded thoroughfares would of necessity be upon a staging erected over the footway. The under frame is carried upon two bogie frames running upon the contractor's rail, by which means it is enabled to turn sharp curves, a guide plate inside the inner rail being provided at the curves for this purpose. The scaffold itself consists of a climbing platform made to travel up or down by means of four posts which have racks attached to their faces, and which are fixed to the under frame and securely braced to resist racking strains. A worm gearing, actuated by a wheel on the upper side of the scaffold, causes the scaffold to ascend or descend.
A railgrip, made to act at the curves as well as on the straight portions of the rail by being attached to a radial arm fixed to the under frame, assists the stability of the scaffold where required, but the gauge of the rails is altered to render the scaffold more or less stable according to its height. Combined with the same machine, and traveling up and down one of the same posts used for the scaffold, is an improved crane. Its action depends upon the proposition in geometry that if the length of the base of a triangle be altered, its angles, and therefore its altitude, are altered. A portion of the vertical post up and down which the crane climbs forms the base of a triangle, and a portion of the jib, together with the stay, forms the remaining two sides. Hence, by causing the foot of one or the other to travel upward, by means of the worm gearing, the upper end of the jib is either elevated or depressed.
The concrete elevator, which is also combined with the scaffold, consists of a series of buckets carried upon two parallel endless chains passing over two pairs of wheels. On the under frame is fixed a hopper, into which is thrown, either by hand or from a concrete mixer running upon the rails, the material to be hoisted, and from which it gravitates into a narrow channel, through which pass the buckets (attached to the chain) with a shovel-like action. The buckets, a motor being applied to one pair of wheels, thus automatically fill themselves, and on arriving at top are made to tip their contents, and jar themselves, automatically into a hopper by means of a small pinion, keyed to the shaft by which they are attached to the endless chain, becoming engaged in a small rack fixed for that purpose. From the upper hopper the material is taken away to the required destination by means of a worm working in a tube. For varying heights, extra lengths of chain and buckets are inserted and secured by a bolt passed through each end link, and secured by a nut. By using this scaffold, a saving in plant, cartage, and labor is effected.
The elevator may also be used for raising any other material besides concrete.
Such is the new system of concrete construction and scaffolding of Messrs. West, which appears to be based on sound and reasonable principles, and to have been thoughtfully and carefully worked out, and which moreover gives promise of success in the future. We may add in conclusion that specimens of the work and a model of a scaffold are shown by Messrs. West at their stand in the Inventions Exhibition. - Iron.
ALBANY BUILDINGS SOUTHPORT. E.W. JOHNSON, ARCHITECT.