Page 26

OF THE PANTHEON AT ROME. 
Septimius; where the columns are as big at the third of their height as at
the bottom: but the 
fwelling of the columns I have no where found.  In the foffit of the architrave
which paffes over 
the columns that clofe the chapels, may be feen how the architrave bears
diredly upon the columns 
at the top and in retreat i-pon the ,pilafters, and after what manner it
returns on the infide of the 
chapels. 
All the profiles of this plate are meafured with the module of the columns
of the order within. 
T H E eighteenth plate reprefents part of the elevation of the attic within
the temple, and the 
profiles of its members at large. It is to be remarked that the fhaft of
the pilafters, and the 
pannels and compartments between them, have no prgje&ion from the plain
of the wall, and that, 
they are diftinguifhed only by the colours of the different marbles of which
they are made; even the 
bafes and capitals projet fo little, that they are but in bas-relief: neither
do the three bands of the 
architrave proje& over each other, being diftinguifhed only by their
colours. This whole attic is 
therefore compofed of four forts of marble; white, ifabella, porphyry, and
ferpentine. The parts 
made of white marble, are the bafement, the focles, the bafes and capitals
of the pilafters, the field 
of the compartments, the jamb and cornice of the windows, the lower and upper
bands and 
cymatium of the architrave, and the cornice of the attic. The parts made
of porphyry, are- the 
pilafters, the friezes between the jamb and cornice of the windows, the rounds
over the windows, 
and thofe of the middle interpilafter. The parts made of ferpentin0 are the
pannels at the top 
and bottom of the other interpilafters, the middle band of the architrave,
the little upright pannels 
at the fides of the circles of the middle interpilafter, the borders of the
great pannels of the other 
interpilafters, and. the borders of the little fquare pannels over the windows.
The parts made of 
ifabella marble, are the infide of the pannels over the windows, the border
of the great pannel of 
the middle interpilafter, and the great pannels of the other interpilafters.
 In this attic as well as in 
the great order within the temple, the projedions or foffits of the mouldings
are the greatefi part of 
them not level, but hang forward. Some of the faces alfo are not plumb, but
incline forward; pro- 
bably to diftinguifh thofe members from each other, and to make their breadths
or heights appear 
greater than they are. I have formerly heard difcuffed, in the Royal Academy
of architedure, this 
queftion of the change of proportions, according to the different afpeds
which height or diflance 
may give to the members of the ftrudures. The opinions were divided: for
fome, following the 
fentiments of the modern architets, faid that in this lies the Whole capacity
of an archited to know 
how to manage that change which muft be always pradifed. Others, following
the advice of Vitru- 
vius in the fecond chapter of his fixth book, infiffed that this is to be
done but feldom ; the circum- 
ftances that admit it, occurring not very frequently. For with regard to
the general propofition of 
the change of proportions, they faid that the judgment of the fight, which
fcarce ever fails, rendered 
that precaution needlefs; as is explained in the notes upon the paflage of
Vitruvius juft cited; and 
even that the change of afpe&s, which is almoft always free, might often
render any artful change 
vicious ; fince, for inflance, if the inclination forward exhibits a face
broad enough at a certain 
diffance, it muff appear too broad When nearer. As to difpenfing with common
rules, occafion, they 
faid, was very rare, to be confined to one afped, as are thofe figures in
optics, of which the parts, 
though -not in proportion, appear well proportioned, from being viewed but
through a hole; that in. 
fhort this inclination of the faces themfelves in all manner of afpe&s
had always a very bad effed, 
when there were angles that rendered it vifible; and that this could be pradifed
only where were no 
angles, as chances in the attic of the Pantheon : that there was reafon therefore
to believe that this 
example taken in an edifice fo well conduted, fo well undertood, and of fo
great authority, had 
prompted the architeds to make a. general rule of a particular inifance,
having paid no attention to 
that uniformity of the cornice, which turning and returning in itfelf makes
no angle; a condition 
without which the inclination of faces is vicious. Notwithftanding thefe
reafons, I fee it a pradice 
generally received to incline the faces of the mouldings, and without fcruple
to difpenfe with the 
l vel, the plumb, and the other laws that render works regular, when it is
imagined that fuch changes 
can produce any good effect. 
All