OF ARTS AND SCIENCES : FEBRUARY 14, 1865. 403 



thorough examination of all the experiments that have been published, 

 or that came within his reach, with the conclusions which have been 

 drawn from them, together with the formulas and rules that have 

 been proposed for practical constructions. Proceeding thus, he has, 

 after a careful and patient examination of the experiments and the 

 reasoning of the several investigations, selected such of the conclusions 

 and formulas as have appeared to him quite trustworthy, and from 

 combining, and, in some cases, modifying these, he has calculated a 

 most elaborate set of tables, by which the architect or practical work- 

 man can find a column suited to any structure, and which may be re- 

 lied upon as safe for all purposes, ordinary, or even extraordinary. I 

 consider the paper thus produced by Mr. Francis as of great value, 

 and believe that it will become a work of the first authority, and of 

 constant reference for the builder. 



This paper might, most properly, have been presented to the Acad- 

 emy by Mr. Francis himself, and I think ought to have been thus pre- 

 sented, without my intervention. He has, however, (probably from my 

 having formerly called the attention of the Academy to the subject, 

 and having been chairman of the committee before referred to,) re- 

 quested me to present the paper for him. I consider myself honored 

 in being thus called upon to communicate a work of such merit to the 

 Academy. Let it be understood, however, that I do not present it as 

 chairman of the committee formerly appointed to examine the subject 

 (this committee have really produced nothing from their charge), but 

 as the sole and private work of Mr. Francis, who alone is entitled to 

 the thanks of the Academy and the community for his most laborious 

 and useful work. 



On the Strength of Cast-iron Pillars, ivith Tables, for the 

 Use of Engineers, Architects, and Builders. By James 

 B. Francis, Civil Engineer. 



Until the year 1840 the only rule in common use for computing 

 the strength of cast-iron pillars was that given by Tredgold, in his 

 essay on the strength of cast-iron and other metals.* This rule was 

 not founded on experiments made on pillars, or on sound theoretical 



* Practical Essay on the Strength of Cast-iron and other Metals. By Thomas 

 Tredgold, London, 1822, and three subsequent editions. 



