270 



DR. L. N. G. FILON ON THE 



in fig. 3. The slab G rested on two knife-edges R and S. On it rested two other 

 knife-edges U and V, supporting a graduated steel bar L Fixed to the top of I was 

 a triangular knife-edge K, from the projecting extremities of which hung two 



---"--* a- ...*.-. ^ 



W 



Fig. 3. 



symmetrical hangers A. These passed through holes cut in the bed-plate P, which 

 supported the whole apparatus, and by means of a cross-piece C and another hanger 

 H a load W was applied which acted on I vertically downwards at its middle 

 point. 



In order to ensure that the reactions between G and the knife-edges B, V should 

 be vertical, the knife-edge R rested on steel bicycle balls B, so that it would readily 

 move under horizontal friction ; V was made a double knife-edge, the plane containing 

 the two edges being carefully adjusted to be vertical. The knife-edge U could slide 

 along I and be clamped in any desired position. When U was clamped and the load 

 applied, the apparatus was perfectly stable, the knife-edge S being kept in its place 

 by the friction of the bed-plate. In order to prevent the knife-edges from cutting 

 into the glass and breaking it under the large loads applied, four small slips of steel Q 

 were inserted between the knife-edges and the glass. These distributed the actual 

 stress without altering the actual statical resultants, and at points near the centre of 



