PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 395 



they will be reduced to a third of the present cost when they are in more 

 general use. There are places where tliey could run very fast, and this 

 saving of time is worth a cent per minute, so that the saving in a daily 

 travel of seven or eight miles would be considerable in a year, 



Mr. J. Bull. — While I agree with Mr. Fisher, and hope that the time is 

 not far distant when city railroads will come into general use, yet I cannot 

 agree with him when he says that city railroad cars are more uncomforta- 

 ble than stages, as I am in the habit of walking some six or seven blocks 

 to the cars every day in preference to the stages close by. 



Explosion of a Casting. 



Mr. James L. Jackson. — Some fifteen years ago I had a casting made of 

 the figure of Mercury. It was cast with a core, and put into vitriol to 

 remove the sand from the outside. The core was never removed, but the 

 opening to the core was plugged up. I had it made as an ornament for 

 Dr. Nott's stove. I found that it would absorb moisture through this plug, 

 and when the figure on the stove would become hot, it would exude from 

 the plug. This figure, I believe, was blackened with varnish twice, 

 Kecently I was doing some work for a gentleman from St. Domingo, and 

 he took a fancy to this figure, when I made him a present of it, and had it 

 removed and sent down to be varnished. While this was being done it 

 suddenly exploded, and came very near killing those around at the time. 

 The best explanation I could give of the cause of this accident was that 

 the core absorbed some of the vitriol, and this formed a gas which gradu- 

 ally increased and finally exploded. At the time it exploded it had not 

 been warm enough to burn the varnish, which was made of oil. The plug 

 was put in at the time it was made, some fifteen or sixteen years ago. As 

 this explosion was somewhat singular, I thought it worth mentioning, as 

 it shows us that we are never out of danger. 



Mr. Dibben. — I do not think that there can be any doubt but that it was 

 the pressure of the steam and not a gas that produced this effect. 



The Chairman announced the subject for the evening, the continuation of 

 the discussion of the "Manufacture of Sugar in the North," when Mr. John 

 W. Chambers read the following paper: 



Production of Sugar at the North. 



No time in the history of the United States will be hailed with more 

 generous welcome than the present for the introduction of any new sugar 

 producing plant. 



Sugar has become so generally an actual necessity of life, and the num- 

 ber of consumers is increasing in such an accelerated ratio, as to cause the 

 demand by far to exceed the suppl}^ Notwithstanding the large quantity 

 of sugar and molasses produced in the United States a large amount is 

 obtained from abroad. The sum paid for imported sugars in 18.59 exceeded 

 thirty-one millions of dollars, and in the same season thirty millions of gal- 

 lons of molasses were imported. 



The following table shows the quantity of sugar, molasses and honey 

 produced in the United States in 1860. 



