OF ARTS AND SCIENCES : FEBRUARY 14, 1865. 



421 



comparison of the safe weights, in tons of 2,000 pounds, which several 

 soUd pillars will support according to Tredgold's table, and according 

 to Ilodgkinson's formulas (1) and (2), taking one fifth of the breaking 

 weight of a pillar with rounded ends as the safe weight. It will be 

 seen that in the smaller pillars Tredgold gives a larger weight than 

 according to Hodgkinson, while in the larger pillars Tredgold's weight 

 is less than Hodgkinson's. It is remarkable, however, considering the 

 origin of Tredgold's table, that they should differ so little. 



Table V. 



In the Journal of the Franklin Institute of Pennsylvania, commen- 

 cing in the number for November, 1861, there have appeared a large 

 number of interesting and useful tables relating to the strength of pil- 

 lars of various materials, computed by the formulas of Hodgkinson, 

 Tredgold, and others, by W. Bryson, Civ. Eng. These tables mostly 

 give the breaking weights of solid pillars. Similar tables of more lim- 

 ited extent may be found in other works, but none of them appear to 

 meet the wants of the practical man. 



Use of the Following Tables. 



The weights are given in lawful tons of the State of Massachusetts, 

 viz. of 2,000 pounds avoirdupois, and are the weights which can be 

 borne with safety by cylindrical cast-iron pillars made with ordinary 

 care and with rounded ends, or what are assumed for this purpose to 

 be equivalent, with ends not finished in planes at right angles to the 

 axis, and the weight not uniformly distributed over the whole area of 

 the ends. 



VOL. VI. 46 



