2832. For the thorough comprehension of a projected edifice, at least three drawings are necessary, the plan, the section, and the elevation. The first is an horizontal section of it, the second the vertical section, which shows the building as if it were cut in half, and that half nearest the spectator, removed from its plan, so as to permit the inner parts to become visible, and the third is the geometrical appearance of the front represented as if viewed from an infinite distance, in which no convergence of the lines would be seen.

G.

2833. In making a design, it is always better to put the general idea together on a single sheet of paper, and consequently, in most cases, on a small scale. This, in afterwards making the drawings, is, as may be necessary, increased in size. The three parts being drawn under one another, as shown in fig. 1013., wherein the middle diagram is the plan, the lower one the section, and the upper one the elevation. By thus beginning on a single sheet, in which the whole is before the eye, the corresponding lines are more readily transferred from one part to another. Having drawn through the middle of the paper the vertical AA, cut at right angles by the horizontal line BB, draw the required centres or axes of the walls CC and DD, and supposing the building is to be square, with the same opening of the compasses set out the axes of the return walls EE and FF. Having determined the thickness of the walls, one half may be set out on each side the axes, as in ee, ff, ec, and dd, and then the lines showing the thicknesses of the walls may be drawn. The width of openings in the walls may be next set out, half on each side the axes BB and AA, first drawn towards bb and aa, and the lines drawn to their places. Having thus Bproceeded, we shall discover that not only has the plan been drawn, but at the same time a considerable portion of the section and elevation. To distinguish the voids from the solids, the latter should be coloured or hatched, and then the next step will be as follows:Parallel to the principal axis BB, draw the ground lines GG and GG. From these lines the heights of the building, its cornice and openings, may be set up in the section and elevation; and afterwards, the height of the roof and projection of the cornice having been determined, they may be set out and drawn. In the section, as in the plan, it is usual either to colour or hatch the solid parts, as we have done in the figure.

}

b

B

D
d

G

-G

2834. Simple as the above process may be, it contains the whole elementary part of the mechanical process necessary for making a design. It might have been conducted on a more complicated mass, but had we done so, it would not have been so well understood, and we therefore deprecate any observations on the simpleness of our process by those who have been brought to know these things by practice and experience. We do not, however, feel we should discharge our duty before closing this section, without a censure on the attempt to convert drawings of geometrical elevations and sections into picturesque representations, because such practice is not only injurious to the art, but is dishonest, and has a tendency to mislead the architect's employer; and we are sorry to say that it is not unfrequently done with such a view. We denounce it, and without hesitation aver that the casting of shadows on a design is only admissible for the purpose of showing the relative depths of projecting parts; and when so admitted, the medium should be confined to Indian ink or sepia, and thrown in merely in masses, the apertures being just slightly filled in with the same

colour.

Fig. 1013.

SECT. III.

CAISSONS IN CYLINDRICAL AND HEMISPHERICAL VAULTING.

2835. Previous to further proceeding, it will be expedient to touch on the method of setting out the caissons or sunken panels in cylindrical vaults and domes, a process required almost in every building of importance, and imparting great beauty to the effect of the interior when properly introduced: it is, indeed, one of the elements in composing them, and must therefore be well understood before the student can succeed in developing his ideas.

2836. In setting out the ribs of cylindrical vaulting, the vertical ones are supposed as falling on supports below the springing; but if such supports fall too wide apart, the caissons themselves will be too wide, and the space must be divided into a greater number; in which case, if practicable, an odd number is to be preferred, taking care that the caissons are not too much reduced in width. This, however, is only for the purpose of ascertaining roughly how many caissons may be used in the circuit of the vault; and it is to be remembered that they must be of an odd number, because a tier of caissons should always extend

along the crown of the vault. Fig. 1014. is an example of a cylindrical vault wherein the number of caissons is five. A is one half of its transverse section, and B a small portion of the longitudinal section. The width of the ribs between the caissons is one third of them; hence, if the number of caissons, as in the example, be five, the semi-arch must be divided into twenty-one parts, one of which parts will be the width of a rib, and three will be given to the width of a caisson. As we have just observed, a caisson is always placed in the centre, we shall therefore have the half-arch = 1+1+3 +3 + 1 = 10 and 10 x 2=21. The vertical lengths of the sides of the caissons thus found will regulate the horizontal lengths of their sides, inasmuch as they should be made square. If the caissons in the vault be seven in number, as in fig. 1015., the sofite or periphery must be then divided into twentynine parts; if their number be nine, into thirty-seven parts; and so on increasing by eight each step in the progression. The caissons may be single or double sunk, or more, according to the richness required; their centres may be moreover decorated with fleurons, and their margins moulded with open enrichments. Where the apartment is very highly orna mented, the ribs themselves are sunk on their face, and decorated with frets, guiloches, and the like, as mentioned for ceilings in Chap. II. Sect. XXIV. Durand, in his Cours d'Architecture, regulates the width of the caissons entirely by the interaxes of the columns of the building; but this practice is inconvenient, because the space may in reality be so great as to make the caissons extremely heavy, which is, in fact, the case in the examples he gives. 2837. In the case of dome or hemispherical vaulting, the first point for consideration is the number of caissons in each horizontal tier of them; and the student must recollect that allowing, as before, one third of the width of a caisson as the width of a rib, the number of parts into which the horizontal periphery (whereof e'e' on the plan A is one quarter, and its projected representation at ee on the section B) is to be divided (fig. 1016.) must be multiples of 4, otherwise caissons will not fall centrally on the two axes of the plan. Thus,

A dome having 16 caissons in one horizontal tier must be divided into 64 parts.
20 ditto

24 ditto

28 ditto

32 ditto

80 ditto.

96 ditto.

112 ditto.

128 ditto.

and so on increasing by 16 for each term in the progression. In the figure the number of caissons is sixteen. The semi-plan is divided into thirty-two parts, three whereof are given to each caisson, and one and a half to each half-caisson on the horizontal axis of the plan. From

10

B

the divisions thus obtained lines are carried up to the section ab, ab, cd, ed. As the projected representations of the great circles of a sphere are ellipses, if from b, b, d, d we construct a series of semiellipses whose transverse diameters are equal to the semi-diameter of the sphere, and their conjugate axes determined from the points of intersection b, b, d, d, we shall have the vertical sides of the caissons. The next part of the process is to ascertain the ratio of diminution in the heights of the tiers of caissons as they rise towards the vertex, so that they may continue square in ascending. Upon a vertical line CC', whose length is equal to the developed length of the line of dome ef, or in other words, whose length is equal to one quarter of the length of a great circle of the sphere, to the right and left of C set out at g and g the half width of the caisson obtained from the plan, and make hg, hg equal to one third of the caisson for the width of the ribs on each side. Draw lines to the vertex of the developement from kh and gg. A diagonal hi being then drawn, the horizontal line ik will determine the lower edge of the next caisson upwards. 1Proceed in this way for the next from l and so on. The heights of the caissons thus obtained, being transferred to the section on the quadrant ef, will give the proportionate diminution thereon of the caissons as they rise. They are discontinued, and the dome is left plain, when they become so small as to lose their effect from below, and indeed they could not beyond a certain limit be executed.

k

C

h

Fig. 1016.

SECT. IV.

HORIZONTAL AND VERTICAL COMBINATIONS OF BUILDINGS.

2838. The different elements of a building are ranged by the side of or above each other, and in designing an edifice both these combinations must be kept in mind, though in the study of the subject, in order to lighten the labour, they may be separately considered. The two species of disposition are horizontal, as in plans, and vertical, as in sections and elevations.

2839. As respects horizontal disposition of the elements of a fabric, beginning with columns, their distance in the same edifice should be equal, but that distance may be varied as circumstances require. In buildings of small importance, the number is reduced as much as possible, on the score of economy, by increasing the distance between them; but in public buildings they should be introduced in greater number, as contributing to the greater solidity of the edifice by affording a larger number of points of support. They ought not, however, to be at all introduced except for the formation of porticoes, galleries, and the like subdivisions. The least distance at which they can be properly placed from a wall is that which they are apart from one another. This distance, indeed, suits well enough when the columns are moderately wide apart; but when the intercolumniations are small compared with their height and the diameter of the columns, their distance from the walls in porticoes must be increased, otherwise these would be much too narrow for their height, affording shelter neither from the sun's rays nor from the rain. On this account, under such circumstances, they may be set from the walls two or three times the distance between the axes of the columns. From this arrangement will result an agreeable and suitable proportion between the parts.

2840. The ceiling of a portico may be level with the under side of the architrave, or it

may be sunk the depth of the architrave, which may return in'a direction towards the walls, thus forming sunk panels in the ceiling, or the sinking of the panels may be as much as the whole height of the entablature, whose mouldings should then be carried round them. When several ranks of columns occur in a portico the central part is sometimes vaulted, the two central columns of the width being omitted. The method of disposing pilasters in respect of their diminution has been treated of in a former part of this work. (2671, et seq.) 2841. The exterior walls which enclose the building should run as much as possible in straight continued lines from one angle to another; a straight line being the shortest that can be drawn. The internal walls, which serve for subdividing the building into its several apartments, should, as much as may be, extend from one side to the opposite one. Where they are intercepted by openings, they should be connected again above by lintels or other

means.

2842. In fig. 1017. is shown the method of forming a plan or horizontal distribution, and combining it with the vertical distribution in the section

and elevation. The thing is so simple that it can hardly want explanation. The equidistant parallel axes being drawn and cut at right angles by similarly equidistant ones, the walls, according to the required accommodations, are placed centrally upon the axes; and the columns, pilasters, &c. upon the intersections of the axes. The doors, windows, niches, and the like are then placed centrally in the interaxes, which must be bisected for that purpose. Above and below the horizontal combination the section and plan are to be drawn. These vertical combinations are infinite, and from every plan many sections and elevations may be formed. The figure exhibits a building of one story only, with a central apartment occupying the height of two stories. But on the same plan a building of two or more stories may be designed. These may have two tiers of porticoes, one above the other, or one only on the ground story, forming by its covering a terrace on the first floor; or a portico might receive on its columns the walls of the next story, and thus become recessed from the main front. So, again, the stories may be equal in height, or of different heights, as circumstances may require. The most usual practice is, above a basement to make the succeeding story higher; but above a principal floor the height of succeeding ones is diminished. The method of placing orders above orders does not require that any addition should be made to what has been said on that subject in Chap. I. Sect. II. of this Book, and by the same methods arcades over arcades may be conducted.

2843. Not the least important of the advantages resulting from the method of designing just submitted to the reader is the certain symmetry it produces, and the prevention, by the use of these interaxal lines on each floor, of the architect falling into the error of false bearings, than which a greater or more dangerous fault cannot be committed, more especially in public buildings. The subterfuge for avoiding the consequence of false bearings is now a resort to cast iron, a material beneficially enough employed in buildings of inferior rank; but in those of the first class, wherein every part should have a proper point of support, it is a practice not to be tolerated. Neither should the student ever lose sight, in respect of the ties he employs in a building, of the admirable observation of Vignola on the ties and chains proposed by Tibaldi, in his design for the baptistery at Milan: "Che le fabbriche non si hanno da sostenere colle stringhe; "- Buildings must not depend on ties for their stability. The foregoing figure is from Durand's Precis d'Architecture. We now submit, in fig. 1018., an illustration of the principles of interaxal division from the celebrated and exquisite Villa Capra, near Vicenza, by Palladio, wherein it will be seen, on comparing the result with what has actually been executed, how little the design varies from it. It will from this also be seen how entirely and inseparably connected with

Fig. 1017.

CHAP. II.

HORIZONTAL AND VERTICAL COMBINATIONS.

777

the horizontal are the vertical combinations in the section and elevation, the voids falling over voids, and the solids over solids. Whatever the extent of the building, if it is to be regular and symmetrical in its composition, the principles are applicable, and that even in buildings where no columns are used; for, supposing them to exist, and setting out the design as though they did exist, the design will prove to be well proportioned when they are removed. The full application of the principles in question will be seen in the works of Durand, the Précis and Cours d'Architecture, which we have used freely; and where we have had the misfortune to differ from that author, we have not adopted him.

2844. The student can scarcely conceive the infinite number of combinations whereof every design is susceptible by the employment of the interaxal system here brought under his notice; neither, until he has tested it in many cases, will he believe the great mastery in design which he will acquire by its use. In the temples and other public buildings of the an cients, it requires no argument to prove that it was the vital principle of their operations, and in the courts, cavædia, &c. of their private buildings it is sufficiently obvious that it must have been extensively used. That its use in the buildings of those who are called the Gothic architects of the middle ages was universal, a glance at them will be sufficient to prove. The system of triangles which appears to have had an influence on the proportions of the early cathedrals may be traced to the same source (see the early translation of Vitruvius by Cæsar Cesarianus), and indeed, followed up to that source, would end in the principle contended for.

2845. It is impossible for us to prove that the interaxal system was that upon which the revivers of our art produced the astonishing examples many whereof are exhibited in our First Book; neither can we venture to assert that it was that upon which our great master Palladio designed the example above given, unquestionably one of his most elegant works; but, to say the least of the coincidence which has been proved between the actual design and the theory upon which it appears to have been founded, it is a very curious, and, if not true, a most extraordinary circumstance. Our belief, however, is, that not only Palladio but the masters preceding him used the system in question, and that is strengthened by the mode (not strictly, we allow, analogous) in which Scamozzi, in the tenth chapter of his third book, directs the student to adopt in buildings seated on plots of ground whose sides are irregular.

2846. To Durand, nevertheless, the public is greatly indebted for the instruction he has imparted to the student in his Précis d'Architecture more especially, and we regret that in our own country the art is treated by its professors too much in the manner of a trade, and that the scramble after commissions has prevented their occupation upon works similar to those which have engaged the attention of professors on the continent. The fault, however, is perhaps not, after all, so much attributable to them as to a government, whatever the party in power, till within the last five years (nay perchance even now) totally indifferent to the success of the fine arts, whose palmy days here were under the reign of the unfortunate Charles. Our feelings on this subject, and love for our art, betray us perchance too much into expressions unsuitable to the subject under consideration, and thereon we entreat, therefore, the patience of our readers, knowing "we have a good conscience."

Fig. 1018.

2847. Our limits preclude the further enlargement on this part of the subject, which in