PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 539 



as produced by the salt, and the railway companies would confer 

 a great boon on the city ; but it must be removed instantly, as 

 soon as thawed. 



One word on the scientific part of the question. The process 

 adopted of snowing and salting simultaneously, is exactly the one 

 most suited to produce the greatest degree of cold, for the time. 

 The more expeditious the thawing the greater the cold. This is 

 necessarily done at all hours, even when the streets are fullest. 

 We cannot avoi,4 the nuisance. It is no answer to say that after 

 so many hours the usual temperature is very nearly re-estab- 

 lished. Again, it is not the same thing whether a foot that is 

 subjected to a given mixture of snow^ and salt is at, say the 

 temperature of this room, or has been previously made as cold as 

 it can bear to be. 



Dr. Vanderweyde read a letter from the Herald, by a contrac- 

 tor for hauling the Hudson R. R. R. cars from Chambers street 

 to Thirty-first street, againfet the use of salt. He said he lost 

 eighty horses by frosted feet, which he attributed to this cause. 



Subject for next week, " Glass." Subject for week after, 

 *' Salting Streets," continued. 



Adjourned. 



American Institute, Polytechnic Association, ) 



March 27, 1862. \ , 

 Prof. Chas. A. Joy in the chair. 



The regular subject of the evening was taken up. 



GLASS. 



The Chairman — I invited a gentleman to give us the history of 

 the art of making glass ; but, a short time before the meeting, I 

 received a note from him, saying that it would be impossible for 

 him to attend ; so, if you will allow me, I will give you a brief 

 sketch of this history myself. The art of making glass dates 

 from immemorial antiquity. The first mention made of it in 

 writing is probably in the Book of Job — in the xxviii. chapter, 

 and the 17th verse. In the 12th verse, the question is asked, 

 "But where shall wisdom be found? and where is the place of 

 understanding ?" and, in connection with the question, the remark 

 is made, in the l7th verse, "The gold and the crystal cannot 

 equal it; and the exchange of it shall not be for jewels of fine 

 gold." Here glass is compared in value with gold and with 

 wisdom. '•' 



