Field Work in Central Africa

THE word new in the title of this article is used in a double sense; it means not, only new bridges, but new kinds of bridges. Speculation on this subject is interesting, and, I believe, useful also, since some of the developments to which it leads appear quite possible (if not inevitable) for the near future. Now the chief reason for the (erection of a new type of bridge is the creation of a new type of obstacle to traffic. To build a bridge for the purpose of crossing an obstacle is nothing new and yet this motive has for some time been quitle overshadowed by another and less elementary. Several factors (the greater speed of traffic being one) contributed towards the beginning the industrial age to make the question of a uniform level the principal one in way making. From that moment bridges were built to take a road over something that wars not in itself an obstacle at all, but merely an actual or a potential inconvenience. It is thus that we get the viaduct and aqueduct, both of which are cast across a valley merely in order to maintain a uniformity of level; whether the one carries a road or a railway, or the second a conduit or a canal, does not materially affect the question. Their purpose differs from that of the earlier bridge in that the maintaining of a fixed level is not a necessity of permanent communication; it is an aid to easy and rapid communication. Nor is the lower way to be compared with the upper, which is as straight, direct and concentrated as the lower (if this can indeed be called a way) is extended and diffused, and consequently it cannot claim the same inflexional courtesy that is always shown to a navigable river confined within definite bounds. The viaduct, and aqueduct, in other words, are typical products of the immediate past, whose chief task was the perfecting of our methods of communication to the farthest possible limit. Christian Barman

A LARGE proportion of the most important new buildings erected in our towns have a steel or ferro-concrete framework. Most architects have not a specialised training in the design of such framework, and it is generally left to the structural engineer to prepare the detailed drawings for this part of the building. As a rule, when it appears desirable that the building should have some architecural pretensions, its design is in charge of an architect who employs the structural engineer to calculate the stresses and strains of all parts of the framework and to specify the sections of the posts and transoms. In this case, however, it is assumed that the architect has determined the general character of the facade on social and aesthetic grounds and only requires from the engineer his technical advice as to the means of making the structure stable. A building may be said to comprise two elements, subject and form, the subject being the function or social purpose of the building, while the form consists in that organic relationship between its parts which results from their compliance with the principles of Number, Punctuation and Inflection, outlined in the last chapter. The extent to which these principles may mould the shape and proportions of a facade will be indicated later. It may be asked "Where does the engineer come in; does not the method of construction also have an important and even determining influence upon the design of the building?" The answer which I am venturing to give to this question may seem extremely paradoxical. It is to the effect that the cleverer and more competent the engineer, to the less extent can he determine architectural style. Where a building continually reminds us that it was constructed in such and such a manner, this is always because in some degree the method of its construction has resulted in some limitation in the shape or size of the members which compose it. In Gothic architecture, for instance, the only style which may justly be described as an engineer's style, the main features which enable us to differentiate this particular manner of building from all others, namely, the pointed arch and vault, grew out of an engineering disability to cover a span in any other way. But the Romans, who were better engineers than our medieval forefathers, not only could manipulate great blocks of stones, but also used concrete with freedom and skill. Some of the famous Roman buildings had the appearance of such self-confidence that they had, it were, a superfluous energy which enabled them to take account of many other architectural factors besides that of purely mechanical strength. And what the Romans did we of this age ought to be able to do, and, indeed, far better, for our resources as constructors are even greater than theirs. A. Trystan Edwards

An interesting example of the application of ferro-concrete cylinders to quay work, has recently been carried out at Tidal Basin- Royal Victoria Docks-where extensive improvements are being provided by the Port of London Authority for the meat trade.