PORTICO. Originally applied without distinction to colonnades and covered ambulatories, the term Is now limited to signify a sheltered space enclosed by colunme at the entrance to a building ; and unless otherwise expressed, roofed with a pediment, like the end or front of a Grecian temple. The term therefore, as now generally restricted, answers to the Pronaos of such a temple.
According to the number of columns In front, porticos are said to be tetrastyle, that is, with four columns ; lwaastyle, with six ; octant yle, with eight ; decastyle, with ten ; and dodeeastyle, with twelve, the greatest number that can very well be brought beneath a pediment; and even of these two List the examples are exceedingly rare. If Instead of columns at the angles there are ante [ANra.:], then the number of columns alone are reckoned as before, and denominates what is equivalent to a portico containing two more : thus a distills hi antis, that is, two columns between two ante, is equal to a tetrastyle, as in both there are three intercolumns; a tetrastyle in antis is equal to a hexastyle, and so on. By means of this simple moods of numerical notation, a couple of words suffice to explain in the cencisest manlier what even a long description may leave doubtful : for instance, when we say that a portico is hexastyle Ionic, we clearly specify the order, and the munber of columns in front ; and it is upon this latter circum stance that so much of particular character depends. By way of example, we instance the following structures : distyle in antis, the church in North Audley Street ; the entrance to the North-Western Railway Terminus, Euston Square, is a magnificent example of a distyle In antis, though not being an entrance attached to a building, it is rather a propylxum than a portico. Tetraetyle, portico of Hanover Chapel, Regent Street; tetrastyle in antis, Law Institution. I Texastyle, the porticos of St. Martin's; St. Coorge's, Hanover Square ; St. Pancras; Post Office ; Italian Opera House, Covent Garden. Octa style, portico of Royal Exchange ; British Museum ; the National ; and decastylo, that of London University College.
Porticos are called prostyle when, as generally happens, they project from the main building. Such as are in antis, and recessed within the front of the building, are technically called loggias ; the latter term indeed is not always employed in this particular sense, but it would lie convenient if It were, as much ambiguity would thereby be prevented The New Town Ilall, Leeds, has a decastylo loggia. Although, too,
a loggia so far resembles any other colonnade, it differs from it In being situated, like a portico, at the entrance and in the centre of a facade, whereas colonnades are usually lengthened ranges of columns in other situations ; thus we speak of the "colonnades" of the Louvre, of Greenwich Hospital, and of the piazza of St. Peter's at Rome.
Psendoprostyle is a useful term suggested by Mr. Hocking for such an arrangement of columns beneath a pediment as resembles a prostyle in elevation, but which, instead of advancing forwards, forms merely a slightly projecting break, the portico itself being within the building, and nowise differing from a recessed loggia, except that it is not in antis, and is crowned by a pediment. Of this kind is the Ionic portico of the East India House, which, instead of being a tetrastylo in antis, is converted into a bexastyle by placing six columns in such manner that the end ones come immediately before the ante or pilasters. The front of the Law institution, Chancery Lane, may also be called pseudo-prostyle, because, although a loggia in antis, it is surmounted by a pediment.
Even in prostyle porticos there Is great difference of character merely as regards the degree of projection given to them, independently of other circumstances ; sonic are made to advance a single intercolumn, and others project considerably more. At the risk therefore of appearing to innovate upon the terminology of architecture, wo would propose the following terms :—monoprostyle, where the portico projects only one intereolumn, as the Ionic heaastyle of St. Pancras church, London ; diprostyle, where the projection is two intereolumns, as in the porticos of St. Martin's, Charing Cross, and St. George's, Blooms bury, and so on ; by which method the portico of the Pantheon at Rome 'night he briefly yet distinctly described as a Corinthian octa style triprostyle, that is, a prostyle with eight columns or seven intercolumne in front, and three open intercolumne at its ends. Another circumstance, which It Is highly important to note, is whether a portico be a simple prostyle, or be likewise polystyk, that is, whether the columns be merely external, or whether there are additional columns within the portico, as is the case with that of the Pantheon, which may therefore be further described as polystylar. The portico of the Kazan church, St. Petersburg, and those of the Glyptotheca at Munich, and Canova's church at I'ossagno, of which plans are given below, are also polystyle.