INTRODUCTION. 



9 



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 connexion 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 illustrations of British Natural 

 History, with an extreme length of 97 x 77, measured into 

 the arms of the cross.. 



"Branching out of the Index Museum, near its southern 

 extremity, are two long galleries, each 278 feet 6 in. long by 

 5 0 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 re- 

 flection 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 terracotta 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 top- 

 lighted 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 smoke-shaft from the heating apparatus, the boilers of 

 which are placed in the basement, immediately between the 

 towers, while the space surrounding the smoke-shafts is used 

 for drawing off the vitiated air from the various galleries 



