Polytechnic Association. 685 



natural cement, but by varying the proportions can adapt it to harden 

 in a longer or shorter time as required ? 



The President — We cannot do it as nature does it. 



Dr. L. Feuchtwanger — It takes nature many years to make 

 erranite, gneiss, or sienite ; and how are we to make these chemical 

 combinations in a few hours ? We have yet to learn how the com- 

 binations take place. We must use a soluble silicate to form an 

 insoluble silicate. If we can do that we can make a good cement or 



artificial stone. 



Adjourned. 



December 8, 1871. 



Prof. S. D. Tillman, in the Chair; Robekt "Weir, Esq., Secretary. 



The following paper by Judge A. L. Hayes, of Lancaster, Pa., was 

 read : 



The Explosion of Steam Boilers ; Causes and Prevention. 

 Vel, tu melius aliud reperi — (Ter. And.) 



Steam power is now generally employed in the most important 

 industrial operations. It has added so much to the material force 

 formerly required for the accomplishment of the diversified objects of 

 labor, and, while it has relieved its severest toils, has so wonderfully 

 augmented its products and the consequent wealth of communities, 

 that it must be accepted as a permanent and indispensable auxiliary, 

 with all the disadvantages inseparably incident to its ordinary use.- 

 Among these apparently incorrigible drawbacks, the most prominent 

 and formidable are the explosions to which steam boilers are liable ; 

 and if there be any method of preserving the invaluable power 

 exempt from that liability, it is surely a consummation devoutly to 

 be wished. 



Although the public are startled by every day's report of some 

 destructive explosion, yet it is doubtful whether many are aware of 

 the enormous sacrifice of human life and immense loss of property 

 caused by those terrible disasters. " We gave," says a recent paper, 

 " from the Hartford Locomotive, a record of the boiler explosions for 

 the year ending October 1, 1868 ; the total of explosions was ninety- 

 four, number killed, 240, number of wounded, 261." A later 

 issue of the same journal gives statistics for the year ending 

 October 1, 1869, which show a total of explosions, 108 ; killed, 158 ; 



