116. The principles governing superposition, or the use of orders one above the other, as we find them in many of the Roman and Renaissance buildings, is that the natural method is followed in placing a lighter and apparently more delicate order above one of greater strength. For instance, the Tuscan should never be other than the lowest order, and the Doric should be placed above this. As we have already seen, however, the Tuscan Order may better be omitted and the Doric Order may be placed in the lowest story with the Ionic and Corinthian above in the order named.

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Fig. 21.

FOUNTAIN OF MOLIERE, PARIS, FRANCE

FOUNTAIN OF MOLIERE, PARIS, FRANCE.

Erected in 1844 to the Memory of the Celebrated Poet, Moliere, who Died in 1673 in a House Located near the Site of the Fountain. The Statue of Moliere, Above, is by Seurre. The Lower Statues, Representing Serious Comedy and Light Comedy, are by Pradier.

Colleonl Porto Palace, Vicenza, Italy; Andrea Palladio, Architect. A Renaissance example of the placing of an Order above an arcade.

Colleonl-Porto Palace, Vicenza, Italy; Andrea Palladio, Architect. A Renaissance example of the placing of an Order above an arcade.

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PLATE XXIII. (A reproduction at small size of Portfolio Plate XXIII.)

Detail of Courtyard, Borghese Palace, Rome; Martiuo Longhi, Architect. Showing Renaissance superposition of arches resting on coupled columns.

Detail of Courtyard, Borghese Palace, Rome; Martiuo Longhi, Architect. Showing Renaissance superposition of arches resting on coupled columns.

117. It sometimes happens that the same order is employed in two different stories, in which case the upper example should be more slender and of less diameter than that below. This rule holds good for any superposition of the orders. Usually the base diameter of the shaft above is the same as the diameter at the neck of the shaft below. In section, or in side elevation, it is the practice to make each order recede slightly from the face of the one below. In other words, the base or square plinth beneath the column in the upper story should be plumb with the face of the frieze of the order of the story below. This gives an appearance of stability which is quite appreciable and prevents the upper orders from seeming to overpower and overweigh the orders below.

118. If columns are coupled and set exactly over each other, there is slight tendency for the space between the columns in the upper story to seem too wide. This may be avoided by taking the center line of the space between the lowest couple and then draw the columns in toward each other on each successive story; keeping them in the same relation to each other and equally spaced on each side of the center line.

119. Facades of edifices of two stories sometimes have an order occupying the whole height of the upper story, the lower story being treated as a pedestal for this order. An example of this combination is seen in Fig. 21. The lower story or ground floor, raised on three steps, is composed of an arcade crowned by an entablature to which may be applied the details of the Tuscan order. Above this entablature is a Tuscan or a Doric order with arches whose axes correspond to those of the lower arches. This order is raised on a double plinth which forms the base of the arcade.

120. The use of an order in the upper story of a two-storied facade offers few difficulties and generally produces a good effect; the proportional height of the base to the order which surmounts it depends entirely on the height of the stories. In this plate the height of the ground story of the facade has been assumed to be six entablatures of the second-story order.

121. The succeeding plates offer an opportunity to study the various methods and combinations in which columns attached to a wall, and called "engaged columns," are used. Such columns were much employed by the ancient Romans in a manner which modern architects have frequently imitated. The engaged columns form a projecting part that in certain instances adds greatly to the perspective effect of a facade, and sometimes serves also as an additional support; but in many instances pilasters would be preferable, especially on the angles of a building. The columns are generally engaged in the walls for from one-third to one-quarter of their diameter.

122. The Romans have also left famous examples of superposition of the orders in the facades of their theatres and amphitheatres, although such a combination is not considered as effective as an order superposed on an arcade, as in Fig. 21.

123. It has been explained that the lower order in a superposition should be a little larger than the one next above it. In Fig. 22 the height of the upper columns is three entablatures seventy-five parts of the lower order, whose columns are four entablatures in height (as is shown by the figures at the left-hand margin).

The same rules have been observed in the two exercises that follow. The Ionic order, placed above the Doric in Fig. 23 is a little smaller than the Doric; the height of the column being but three Ens seventy-five parts of the lower order. The Corinthian column placed on the Ionic in Fig. 24 has but three Ens seventy parts of the height of the Ionic. This will give in each instance for the column of the upper order a lower diameter that is substantially the same as the upper diameter of the column over which it is placed. At the same time the height of the second story, as well as the arches and column there used, is reduced proportionally, unless the column shafts be attenuated beyond the rule here employed

124. Taking the height of three entablatures and seventy-five parts of the first story order, for the total height of the columns in the second-story order in Fig. 22 by re-dividing that height into four parts, it is easy to ascertain the height of the second-story entablature in relation to the column with which it is used.