[Read before the Hoy,,! Sucety ,,/ X. S Walrs, Deceynher 7. 1910.] 



These tests were carried out by Professor Warren and Mr. 

 J. MacD. Royle, B.B., with a view to obtaining the relative 

 values of timbers for wood-blocking, flooring and similar 

 purposes. It is very difficult to get a suitable test for these 

 properties of materials, but of all tests so far devised the 

 sand blast method appears to be the best, as the material in 

 this method is actually worn away by abrasion. It is 

 possible to block, for instance, different parts of the same 

 street with different timbers, but experiments like these 

 would necessarily last several years in order to obtain 

 results of any value as far as the resistance to wear of the 

 various timbers is concerned, and even then it would be 

 most difficult to say that the different kinds of timbers had 

 been subjected to the same conditions. 



Description of the Apparatus. 

 A general view of the sand blast apparatus is shown in 

 (Plate 52) and a diagramatic view in (Plate 53). The 

 apparatus consists essentially of a nozzle through which 

 sand can be propelled at a high velocity by means of a jet 

 of steam. This is carried out in the following manner:— 

 Steam from the boiler (not shown) enters the cylinder a at 

 b (Plate 53). Part of this steam flows straight to c where 

 it exhausts to the atmosphere through a nozzle, thus causing 

 a partial vacuum around c. The remainder flows up through 

 a valve at d, tray e and nozzle f to the expanding nozzle g, 

 where it gets completely dried and superheated. The sand 



