104 Mr Fairbairn on Fireproof Warehouses. 
props which support the floors have their ends placed im- 
mediately under the main beam ; and these being successively 
supported upon each other, with the main beam intervening, 
the result is, that the fibres of the girders are thus com- 
pletely crushed, particularly in the lower floors, by the su- 
perincumbent weight, and, in many cases, the beams are 
almost squeezed in two from the immense pressure to which 
they are subjected. Even in this imperfect construction, the 
necessary precaution of wooden caps has not, in all cases, 
been adopted ; and until the introduction of iron columns, 
with heads and bases covering a large surface of the beam, 
the timbers were, in many instances, seriously injured. 
The use of iron columns, although an improvement upon 
the old system of building, is, nevertheless, no security 
against fire, and it is obvious that no guarantee can be given 
so long as the structure is chiefly composed of timber, and 
the openings imperfectly closed by wooden doors and shut- 
ters. From this it is evident that, in order to give perfect 
security, warehouses must be constructed upon different 
principles, which may be enumerated as follows, viz. :— 
1. The whole of the building to be composed of non-com- 
bustible materials, such as iron, stone, or bricks. 
2. In order to prevent fire, whether arising from accident 
or spontaneous combustion, every opening or crevice com- 
municating with the external atmosphere to be closed. 
3. An isolated stone or iron staircase (well protected on 
every side by brick or stone walls) to be attached to every 
story, and the staircase to be furnished with a line of water 
pipes communicating with the mains in the street, and as- 
cending to the top of the building. 
4. In a range of stores, the different warehouses to be 
divided by strong partition walls, in no case less than 18 
inches thick, and no more openings to be made than are ab- 
solutely necessary for the admission of goods and light. 
5. That the iron columns, beams, and brick arches, be of 
strength sufficient not only to support a continuous dead 
pressure, but to resist the force of impact to which they are 
subject by the falling of heavy goods upon the floors. 
Lastly, That in order to prevent accident from intense 
