776 KANSAS CITY REVIEW OF SCIENCE. 



the lower surface of the plank so as to leave no empty concealed spaces in which 

 fire can find a hidden lodgment and way to spread. The modern Roman floors 

 are very generally laid on stout, rough beams, flattened on top, placed at such 

 intervals that the broad, thin bricks or tiles used in Italy can be laid so as to span 

 the openings between the beams ; a second layer of bricks or tiles laid in mortar 

 (all Roman mortar is a cement of sand, lime and puzzolana, a volcanic cement) 

 completes the strength of the floor. It is in the better houses finished with mar- 

 ble tiles or with a fine concrete of cement, lime, sand, and broken bits of mar- 

 ble, of red, hard-burned bricks, or of pottery, which, after setting hard, is rubbed 

 down with sand and polished, making either a closed imitation of breccia marble, 

 or, if red brick or pottery broken from the body of the stucco, then 'it is what the 

 Romans in Pompeii called opus signinum. The ceiling belo v is plastered and 

 the floors are almost incombustible. 



All stone stairs and posts are dangerous in great fires. Limestone calcines, 

 sandstone cracks, granite and sate explode into fragments. Captain Shaw, of 

 the London fire brigade, in an excellent treatise published in 1872, stated that 

 his men were not permitted to enter, in case of fire, warehouses in which there 

 were iron or stone story-posts or floor-beams, or even to attempt to use stone 

 stairs. He had seen stone stairs lying in 3, heap at the bottom of the stair-well 

 after a very moderate fire. In Rome the stairs are universally of brick. The 

 landings are brick arches of very slight rise turned across the ends of the stair- 

 well or staircase, the flights of stair rest on inclined, rampant brick arches spring- 

 ing from the edge of one landing to the next above at the other end of the well. 

 The upper surfaces of these arches are brought to the form of a flight of steps. 

 For beauty, the treads, and sometimes the risers also, are made of thin slabs of 

 stone, generally either travertine stone or marble, which is abundant and cheap 

 in Italy. These are very handsome, stately stairs, not very costly, and as nearly 

 fire-proof as can possibly be bui t. 



There is another thing in connection with floors, and that is, that they should 

 be so constructed as to be in a measure water-tight, and on the same principle as 

 the deck of a ship, so that in the event of a fire in the upper stories the damage 

 which now necessarily ensues, by reason of the deluge of water applied, may be 

 obviated; in other words, let the floors of buildings be caulked, so that they should 

 be perfectly water-tight, and whether water should be spilt by accident or by de- 

 sign, as in the case of fire, no damage to the goods stowed beneath would occur. 

 The first thought which occurs to one is, that in the event of a hose being turned 

 on to an upper story, the water, finding no outlet, would flood the room to any 

 depth, but the providing a gutter round each room communicating with pipes 

 piercing the walls and carrying away the water as a rain-water pipe now does, 

 would remove this danger. No doubt were this plan carried into effect, the first 

 cost of erection would not be somewhat increased, but to the person intending to 

 use any particular house for the storage of valuable and perishable property, it is 

 well worthy of consideration whether it would in the end " pay" to adopt the 



