OF IRON BEAMS. 423 



'>;I then got a very light piece of wood, in the 

 form of an isosceles triangle, ELM, whose 

 altitude was about 3 feet 6 inches, (the length 

 of the board J and its base LM 10 inches. 

 Along the side of LM there was nailed a piece 

 of tin, perforated with a row of holes, so as 

 rather loosely to fit the ends of the springs 

 projecting through F, and this tin was slid upon 

 them. The board ABCD was then raised per- 

 pendicularly to the horizon, its edge CD being 

 uppermost, and having the triangular piece 

 ELM sliding along its side, and attached to the 

 board only by the springs : the end AD of the 

 board serving to render the triangle steady, 

 and, (by means of a pointed instrument passing 

 through the latter) to hold it, if necessary, in 

 any position. 



I then hung a small weight at the end E, and 

 there being nothing to support it and the weight 

 of the triangle, but the springs, the point was, 

 as might be inferred, carried some distance 

 down, the upper springs being drawn after 

 the base of the triangle, nearly in the direction 

 CD, and the lower ones made to recede in 

 the opposite direction ; the whole turning as 

 it were on the central spring, which was not 

 bent, and consequently supported nothing. 



