Art. X. — On the best Form for a Balance Beam. 

 By Professor Kernot, M.A., C.E. 



[Read 12th JiUy, 1894.] 



On the 13th May, 1880,* I submitted to this Society a paper 

 on the above subject in which the problem of designing a balance 

 beam of minimum mass for a given strength and rigidity was 

 discussed, and a form was suggested very different from those in 

 general use. This result was arrived at purely by mathematical 

 reasoning. It appeared at the time desirable to verify this 

 reasoning by actual experiment, and models were prepared for the 

 purpose, but the appliances for making the experiments being of 

 a very imperfect kind difficulties arose in making the tests, and 

 the whole matter was laid aside. Recently, however, there has 

 been an opportunity of reopening the question, and with tha aid 

 of the large and very perfect testing machine belonging to the 

 Engineering department of the University, a number of experi- 

 ments have been made which I now propose to describe, and 

 which bear out the conclusions of the paper. Four models were 

 obtained of cast gun metal, and of about the same weight. Two 

 of these represented the form advocated in the paper, while the 

 others represented the type shown by Fig. II. in the diagram (see 

 p. 22, of vol. xvii.. Transactions). 



The results were as follow, the beams being one foot long : — 



Load at each end of beam Ultimate 



at moment of failure. deflection. 



1. De.sign advocated, Fig. 3 \ 



of diagram. Weight I ... 8821bs. ... -06 inch. 

 12ioz. ... '...) 



2. Design advocated, Fig. 3 \ 



of diagram. Weight '• 

 13|oz j 



3. Old form, Fig. 2 of dia- 



gram. Weiffht 12A^ oz. 



« Transactions of the Royal Society of Victoria, vol. xvii., p. 19. 



lOSolbs. ... -07 inch. 



4131bs 4 inch. 



