thrive than facts, we deem it our duty to draw the attention of our readers to this subject. We would add, that the term truss is no more correct, when applied to the work of the bracket, than are the others. A truss has reference to a heavy framing; and should not be confounded with a light support. Ancone is still another name for this object; but it is little known and less used; so we will not waste time on it.
Brackets answer a very good purpose, both inside and outside of a house; and have, of late years, grown greatly into favor, in the composition of country houses. In fact they have been made the feature, in so much, that our English critics denominate a composition in which they are much used, "American bracketed Architecture." We find no fault with this; but we do denounce the excess to which some builders carry the use of this otherwise pleasing and certainly very useful feature. We have seen roofs of two story buildings project fully three feet. Thus giving a very bad effect to the whole house. Even at five stories such over-hanging eaves would be faulty.
Brackets are capable of receiving much embellishment; but it must be of that order, which will not lead the mind to suppose, that any part of their duty is to support their own ornamentation.
Grace of curvature is the chief object to be kept in view, in their outline or general shape. And there are few things that call forth the artistic taste of a designer more than this very bracket. Nature's exquisite curvatures of long foliage, meeting with obstruction, will present charming hints for the free pencil, guided by judgment and skill.
CENTERING.
Nothing in the scientific range of Carpentry demands more attention, than the problem of Centering; or the construction of a framing, on which arches of stone, or brick, are to be turned. When we consider the weight to be borne, the pressure to be resisted, and the imperative necessity for accuracy of curve, it will be at once seen, that it is by no means a trifling matter.
The most eminent engineers and architects have made this subject their study. Nor is it alone in large constructions, such as aqueducts and bridges, that it is to be pondered, and wrought out; but in the smallest arch its peculiar characteristics are to be seen and attended to. Every round-headed opening in a building has to be turned on a centering, so that much depends upon its strength and accuracy. There must not be a possibility of the slightest change of form. The centres must be easy of removal, and as economic, as is consistent with the requisite strength.
The following problems will be found useful in relation to centering:—
To form a true Ellipsis, on a given Base,
with a given Height.
Fig. 1. Let A B be the given line; D C the given height: Take off from B to D equal to this height, D C ; divide the remaining portion, towards D, into three equal parts; give one of these parts to lengthen the distance from D to B; call this new point F. Now take the distance from D to F and mark it off on C. Next take C and F, as centres respectively, and the distance between them as radii, and describe arcs crossing each other at H. Join H F, and H C, and continue the lines to I and G respectively. Lastly: Taking H as a centre, describe the segment I C G; and, taking
