DESCRIPTION OF THE BUILDING. 
13 
" On entering the main portal, the visitor has before him the interior, 
great central apartment of the Museum (170 feet long, by 97 feet Central HaU. 
wide, and 72 feet high), which it is intended to use as an Index or 
Typical Museum. The double arch in the immediate foreground 
which spans the nave (57 feet wide), carries the staircase from 
the first to the second floor. Opposite the spectator, at the end 
of the hall, is the first flight of the staircase, 20 feet wide, which 
rises from the ground to the first floor. The galleries over the 
side recesses form the connection between the two staircases, 
and are also intended for exhibition space, as are also the floor of 
the main hall and the side recesses under the galleries. The 
arches under the side flights of the main staircase at the end of 
the hall lead into another large apartment, cruciform on plan, 
intended for the exhibition of specimens of British Natural 
History, with an extreme length of 97 by 77 feet measured 
into the arms of the cross. 
^' Branching out of the Central Hall, near its southern side galleries, 
extremity, are two long galleries, each 278 feet 6 in. long by 
50 feet wide. These galleries are repeated on the first floor, and 
in a modified form on the second floor. They are divided into 
bays by coupled piers arranged in two rows down the length of 
the galleries, and planned in such a manner as to allow of upright 
cases being placed back to back between the piers and the outer 
walls, so as to get the best possible light upon the objects 
displayed in the cases with the least amount of reflection from 
the glass, and leaving the central space free as a passage. 
Owing to the nature of the specimens exhibited in one or two 
of these galleries requiring for their exhibition rather table- 
cases than wall-cases, advantage has only been taken to a 
limited extent of this disposition of the plan. These terra-cotta 
piers, however, are constructively necessary, not only to conceal 
the iron supports for the floor above, but to prevent these 
supports being affected in case of fire. Behind these galleries 
on the ground floor are a series of toplighted galleries, devoted, 
on the east side to Geology and Palaeontology, and on the west 
to Zoology. 
" The towers on the north of the building have each a central Towers, 
smoke-shaft from the heating apparatus, the boilers of which 
are placed in the basement, immediately between the towers, 
