1600
THEORY AND PRACTICE OF ENGINEERING.
Book IT.
occupy one-half the width, and the piers the other: where the diagonals of the figurecross is the centre, from which the principal arch is struck.
The Arch of Trajan at Beneventum . — Circle struck from the centre which describes thearchivolt; comprises all within it except the attic : division of width into seven, two for eachpier, three for centre ; attic half the height of the order.
In the foregoing examples, we have attempted to show that the beauty which belongsto form in architecture rests upon one principle based on the laws of nature, and that thefirst element in a good design is the proportion of the parts as well as the whole: nothinghas more misled the critics upon this subject, as well as architects themselves, than im-plicitly following the rules laid down for drawing the orders. In treating upon theantique, they have frequently been right as far as regards the letter, but essentially wrongin the spirit. The laws of nature do not vary, nor do our organs of sense or perception,and what was apparently fit and proper in the opinions of the Greeks is equally so at thepresent day : in their sculptures we never find a man represented carrying more than hisown weight, and such laws ought to be our guide.
After the destruction of the Roman empire, the character impressed upon architectureby the Greeks was lost: other styles arose in succession, which have been designated asByzantine, Romanesque, Lombardic , Saxon, Norman, Saracenic, and Pointed. The fivefirst retained the semicircular arch, and only differed in the quantity of material em-ployed : for examples of the three first-mentioned we must refer to a work entitled“ Architecture of the Middle Ages at Pisa,” by Edward Cresy and G. L. Taylor, containingmeasurements made in 1817, in which is an engraving of the monument of the architect■who executed all the work in the pointed style introduced in the celebrated baptistery,supposed to have been the work of the twelfth century ; the discovery of this monumentsatisfactorily proved the date when that building was altered from the original Romanesquecharacter.
In England the Saxon style prevailed to the time of the Conquest (106'6), and the Norman,which succeeded, varied but little from it. The pointed arch is found as early as 1180 ;after which the Lancet style became general, and continued to be used till about 1272 ; tothis succeeded the decorated or geometric, which was practised till 1326, when the perpen-dicular style was universally adopted, and continued till the early part of the sixteenthcentury, when classic architecture was again revived. Our attention must not, however, bedirected to the decorative portions of either style, but to the construction, from the study ofwhich some valuable lessons may be deduced.