.">S 50-TON HUCKTON MACHINE. 



of this movement from the normal position shown in the 

 figure, to the extreme position of the right-hand end of 

 the beam, is 



50x3= 150 in., 



which is equivalent to a maximum pull upon the specimen 

 of 50 tons. 



The pull on the specimen bein<* 50 tons, and the poise 

 weight 1 ton, when the full load is on the specimen the 

 effect is the same as would be produced by a simple lever 

 whose length of the arms were 150 in. and 3 in. But, when 

 the poise is at the negative end of the lever, it is balancing 

 the neavy end, which is itself equivalent to 1 ton hung at 

 the end of the otherwise balanced lever. So that when the 

 poise has moved to its full extent, the actual weight used 

 for measuring the stress is really double that of the poise, 

 or 2 tons, and the actual leverage is 



50 o- * 

 , or 2o to 1 

 Jt 



It will be seen that any variation of the magnitude of 

 the load upon the specimen depends upon only the position 

 of the poise-weight, which itself is invariable. In order, 

 therefore, that the operator may be able to ascertain and 

 observe the load, a steel graduated scale is attached to the 

 side of the beam, by means of which the position of the 

 weight, and therefore the magnitude of the load, may be 

 gauged. The scale of the machine in question is divided 

 into equal lengths of 3 in., each equivalent to 1 ton ; each 

 of these tons is subdivided into tenths and twentieths ; 

 and by means of a sliding vernier attached to the moving 

 weight further subdivisions into hundredths and two- 

 hundredths of a ton may be effected. In all machines of this 

 type the position of the vernier is made adjustable, so that 

 when the poise weight has been brought to such a position 

 that the beam is in perfect equilibrium, previous to a test, 

 the vernier can be set with its zero point coinciding with 

 the zero of the main or parent scale. This adjustment is 

 often rendered necessary in the case of some tests, such as 

 those in compression and bending, when extra heavy 

 tackle has to be hung from the shackles and the beam is 

 thrown out of balance ; this state of things also exists 

 when very heavy specimens are being tested. 



In order that the position of the weight may be truly 

 indicative of the load upon the specimen the beam must 



