THE FIHEPROOFING OF CITY BUILDINGS. 5tSl 



of cori-iigatecl flooring is " Lindsay's patent steel decking " which 

 consists of S[)layed steel channels rivetted together. It is covered 

 with concrete, and will span from twenty to fifty feet, without 

 girders. The metul is, howe\'er, exposed on tlie underside, uidess 

 a false ceiling of wood and plaster, or concrete is formed under- 

 neath. The only example of this construction in the colonies, so 

 far as I am aware, is in Mr. Paling's new buildings, near the Post 

 Office, Sydney. 



y. The honour of inventing the most perfect fire-proof floor 

 as yet introduced, must, I think, be accorded to the Americans. 

 It consists of straight keyed arches of hollow terra-cotta blocks, 

 which All in between the rolled iron joists. The girders, and the 

 lower flanges of tlie joists are protected by linings of the same 

 material (PI. XXXIX., flg. 12), kept an inch or so away from the 

 surface of the metal. This floor is very light, strong, and practically 

 tire-proof, the air-space between the terra-cotta and the iron prevent- 

 ing the transmission of heat. In 1870, a girder for the National 

 Safe Deposit Company, of London, protected as just described, was 

 tested by flre with the most satisfactory results, and since then this 

 system has grown rapidly in favour.* This was the first example 

 of the construction in England, but whether borrowed from the 

 Americans or not, I cannot say. A great improvement which the 

 Americans have undoubtedly introduced is the material known as 

 porous terra cotta. It is simply clay mi.'ced with saw-dust, or other 

 vegetable matter, which is consumed in the burning of the blocks. 

 They are thus honeycombed, and are muchlighter and more heat- 

 resisting than ordinary terra cotta. The best known American 

 systems are those of the Wight Fire-proofing Company, and 

 *' Henry Maurer and Co.," who both adopt porous terra-cotta. 

 In England, the Doulton-Peto system is precisely similar to the 

 American, but is carried out in ordinary terra-cotta. The Araeri 

 can systems are represented by a company in Melbourne, and 

 the Doulton-Peto by an agent in Sydney. During my last visit 

 to Melbourne, I noticed that porous terra-cotta of local manufac 

 ture, or terra-cotta " lumber," as it is called, is being used in one 

 or two buildings, though as yet it leaves something to be desired 

 on the score of accuracy and finish. As in tlie coke concrete 

 flooring, so with this, there is no need for a false ceiling, because 

 the plaster or cement can be laid straight on to the terra-cotta, 

 which, if porous, affords an excellent hold. A further precaution 

 is to prepare the blocks with dove-tailed grooves, and so increase 

 the key. Although the most expensive of any floor, it is, in my 

 opinion, the most fireproof, and therefore should be adopted when 

 the greatest safety from fire is desired. 



A. All the systems I have just described can be finished with a 

 wooden floor, when desired, by laying ordinary wooden joists on 



* See Appendix D. 



