ON THE EAUTIIQUAKE AND VOLCANIC niENOMEXA OF JAPAN. 311 



diagonal of their plan. A result like this might bo obtained by laying 

 out the streets and roads in proper directions. Rossi suggested that the 

 most resistant sides of buildings .should be placed at right angles to the 

 nearest line of volcanic fracture, he holding the opinion that earthquake 

 vibrations were propagated normally from the lips of such fractures. 



The suggestion that buildings should have a rectangular plan or be 

 simple in form is a suggestion worthy of consideration, for it would 

 certainly seem that such a building would be subject to less destructive 

 stresses than one which was largely built up of wings and other project- 

 ing parts, no two of which could be expected to vibrate in nnison. 



As to whether any great good may bo gained by giving a building a 

 proper orientation is not certain. In Tokio it appears that walls running 

 in certain dii-ections have been cracked more than others, and also that 

 at the time of great earthquakes there has been more destruction in 

 streets running in particular directions. Streets ought certainly to be 

 wide, inasmuch as they would then form a refuge from falling debris. 



11. Floors. 



In Ischia it was suggested that floor-joists should rest with their 

 whole thickness on the walls. If possible, joists should cross each other 

 at right angles, and the floor-planking be laid diagonally. 



Bertelli proposes a system of flooring of iron beams connected by 

 brick vaulting, or in place of this ordinary joists and planking. The 

 beams on one story should be placed at right angles to those on another. 

 In all cases the joists are to extend completely through a wall. This 

 regulation is also contained in the Norcian edict. 



From these notes it appears that the intention of the authors of the 

 regulations has been to utilise the floors to bind the building together as 

 a rigid whole, and allow joists to extend so far into walls that there is 

 no danger of their being drawn from their supports. 



12. Ceilings. 



Ceilings should be made in the ordinary manner with laths and 

 plaster. But heavy ornamentation should be avoided. 



13. Staircases. 



Although staircases, if they are heavy, might prove a danger to walls, 

 their construction has not been regulated by legislation. Bertelli sug- 

 gests that they should bo constructed of pieces bedded in the walls, as in 

 the Tuscan system. If made by vaulting they arc dangerous. 



14. Materials. 



In all regulations special stress is laid on the quality of materials 

 employed, and in all cases it is specified that these should be of good 

 quality. The Ischiau regulations specify that for the principal frame- 

 works of building chestnut must be used. In all cases square stone is 

 to be employed. The lime must be good, and be properly slaked with 

 fresh water. Below ground hydraulic mortar must be used, and the sand 

 used in making mortar must be clean. These matters are treated upon 

 in all regulations. In the regulations for Manila we find special remarks 



