4*12 TRANSACTIONS OF THE 



not opinion. The engineer must act on such judgment. The commitfcc 

 will have to explore a very wide field. The information as to the stone of 

 the locks at Lockport is useful. Facts alone must he made to constitute, 

 as it were, a ipavement to stand on. I suggest the thorough study of the 

 nature and action of cements as of very great importance, for, figuratively 

 speaking, it has hecome a mere roft of sand ! In research, facts come 

 before us ramifying like a tree from branchute twigs. Professor Mapes 

 undertook to define the cohesion of cement and its blocks, bricks, &c,, to 

 be a sort of minute dove-tailing of the particles of sand with the building 

 material. This I do not comprehend. In all glues and cements, what is 

 the law of their cohesion ? 



Engineer Everitt. — I entertain a hcly horror of the symbols in modern 

 ■use for the science of the constituents of bodies. I am not ready to-night 

 to give such facts as I wish to submit. 



Prof. Hedrick. — What is cohesion in a diamond ? Mortar well made 

 becomes gradually harder than stone. I have made some things, but I 

 have not made a book yet ! I have built a house of Thomastown lime and 

 the loose stones on my fields mixed, pressed into moulds, and then made 

 walls of it. The cement being kept several weeks, set the better for it, 

 I used one part of lime to sixteen parts of sand. My neighbors laughed 

 at me for putting in some round stones, and wanted to know why I did not 

 break them I I kept ray mortar three or four weeks before putting up wall, 

 and it set well. Climate has much to do with it. A Roman house would 

 not stand in New York. 



Mr. Garbanati. — The mortar question is all-important, but the construc- 

 tion of our walls vastly more so. Look at the inner part of them filled 

 with comparative rubbish, with a thin epidermis skin of marble or brown 

 stone, or even good brick. It has no strength or durability. The fine 

 looking city hall of Brooklyn is only a skin of marble, and is already 

 decaying. On the plan of Prof. Hedi'ick we can make strong walls better 

 than disjointed stones. The great acqueduct of Brooklyn, which should 

 not decay for centuries, has in some parts room enough for the passage of 

 rats through it ! 



Mr. Bruce. — Sand from the sea shore has been improperly used in mor- 

 tar. The salt in it ! The first shot tower built by Mr. Youle here, used 

 it, and soon after crushed all down ; and walls made with such mortar are 

 always wet. 



Mr. Wilmarth, of Brooklyn. — Notoriously wet. I use one part coal 

 ashes, one sand, and one lime, for mortar. I mis by iron rollers revolving 

 in a pan, having scrapers attached to scrape up the mortar before the rollers' 

 constantly. The mortar becomes smooth and soon sets firm. 



Mr. Garbanati thought that our sea sand would be more useful spread 

 on our roads. 



Mr. Everitt. — Chloride of calcium, with salt, will retain moisture for 

 years. 



Prof. Mason. — A man in New Haven makes mortar of good quality.. 



