630 PROCEEDINGS OF SECTION H. 



3.— THE HOLDING POWER OF NAILS AND RAILWAY DOG SPIKES 

 IN NEW SOUTH WALES HARDWOOD. 



By PROFESSOR WARREN and MR. H. A ROBERTS, B.E., Assistant Lecturer and Demonstrator 



in Engineering. 



(abstract) 



The holding power of nails or spikes in timber depends upon the 

 friction that can be developed between the fibres of the timber 

 and the surface of the driven nail or spike. The friction increases 

 with the pressure exerted by the fibres, and this latter is influenced 

 by the elastic properties and strength of the timber. In all the 

 New South Wales hardwoods it is necessary to bore a hole slightly 

 less than the nail or spike to be driven, otherwise they would 

 probably bend or buckle. In soft woods, on the other hand, it 

 is not necessary to bore a hole. 



The nail was withdrawn in a testing machine, using the ordi- 

 nary steel wedge grips, as in the tests of fiat specimens. 



The tables of results show that grey ironbark is the best 

 timber for holding power, and that blackbutt, tallow- wood and 

 grey box are each about 20 per cent, below ironbark. The holding 

 power differs in the same timber in the three directions relatively 

 to the annual rings, being greatest when driven parallel to the 

 layers of fibre, and shghtlyless when driven perpendicular to the 

 layers of fibre, as in sleepers and flooring boards. 



It was found that the ordinary round and square spike used 

 on railways and tramways respectively was much inferior to a 

 special twisted square spike, known as the " Floessell spike," the 

 latter having 35 per cent, greater holding power. 



This paper included many tables of results, and it was illus- 

 trated by numerous diagrams. 



4.— HARDNESS OF NEW SOUTH WALES TIMBERS. 



By PROFESSOR WARREN and MR. G. E. COWDERY, B.E., formerly Demonstrator in 



Engineering. 



(abstract) 



It is well known that what we call the hardness of material is a 

 quality difficult to define in an exact manner, as there is no absolute 

 standard of hardness. In this investigation the hardness of the 

 timbers has been compared with reference to the three planes as 

 foUows : — 



A. — Parallel to the fibre. 



B. — Perpendicular to the annual rings. 



C— Parallel to the annual rings. 

 Three methods were used : — 



The cross-compression test, or the sleeper test, as it is some- 

 times called, because it is almost identical with the indentation 

 produced by the bottom of the rail pressing on the sleeper. 



