Use of The Orders
It was early discovered that the shaft of a column appeared more graceful if it diminished in diameter from base to capital. Most Renaissance authorities agree that this diminution should amount to one sixth of the base diameter (though Perrault allows rather less). I have adopted as a near metric equivalent of this a diameter at the head of . times the base diameter. It is not always clear at precisely what point this uppermost diameter should be measured, but I have assumed throughout that it is most logical to imagine the column length ‘produced’ through the capital to its junction with the entablature. Hence the breadth of the entablature is directly determined at . times the base diameter, whereas if the upper diameter is measured below the capital the dimension of the entablature is left indeterminate.