Polytechnic Association Proceedings, 795 



a half times the strength of wi'ought ii'on bars of the same dimen- 

 sions. He determined the relative value of these two materials, 

 taking the cost of iron at thirty-five dollars per ton, and steel at 

 SLxty dollars, and found that iron would be about one and a third 

 that of steel. In the case of railway bars, and such constructions, 

 besides this saving in the cost of material, it must be borne in mind 

 that the steel rail would last four times as long as the iron rail. 



Taking the mean results of the experiments on thirty of the best 

 specimens with regard to tensile strain, he found the mean tenacity 

 per square inch equal to 47.7 tons. Taking twenty-five tons per 

 square inch as the tenacity of the best English hammered iron, it 

 follows that the tenacity of the steel bars is nearly twice that of 

 iron bars. 



The results with regard to compression, show that thirty-two of 

 the bars supported a pressure of 100.7 tons per square inch, while 

 twenty-three bars were more or less fractured by this pressure. 

 The mean value of the unit of strength in short columns is 33.4. 

 It was calculated that the work expended in rupturing the material 

 by compression, is about five and a half times that expended in 

 rupturing similar material by extension. The resistance to com- 

 pression was found to be more than double that to extension; hence 

 it follows that the most economic form of a steel bar underoroing: 

 transverse strain would be a bar with double flanores, having: the 

 area of the bottom flange about double that of the top flange. 



Mr. D. W. Bradley read the following interesting paper on 



THE TOWER CLOCKS OF NEW YORK CITY. 



Mr. Chairman: While invitmg you to take a tour among the 

 towers with me this evening, I can assure you I feel my inability to 

 make that tour interesting; my descriptive powers are limited. 

 Some time since I jotted down a general description of the tower 

 clocks in New York, with some facts and fancies concerning them, 

 and I propose to give you them very nearly as I jotted them down, 

 although in copying I did try to work out some of the fancies. So, 

 if you find anything in this foreign to the subject, I must beg you 

 to forgive me, as it was written and intended only to occupy a space 

 in a private diary. 



My first thought is the old saying of Franklin, that " Time is 

 money." Now, with all due deference to the great philosopher, I 

 would say, Time is education. Time is improvement, progress, 

 science, art; and, on the other hand, time is idleness — time is dis- 



