214 TRANSACTIONS OP THE AMERICAN INSTITUTE. 



is large and round (average 1^ inches diameter), and very good, but it is 

 green and hard as a stone when all others are ripe. It is a prolific bearer, 

 but quite scarce. I have seen only three trees, and those small, although 

 I have traversed the timbered portions of the State considerably. I find 

 the wild plum runs to variety; the seeds of one tree produced four different 

 sorts of different color, size and quality. One of your correspondents says 

 the wild plum is not affected by black knot, but I have seen many that 

 were entirely destroyed by it. The wild cherry is also affected. It is 

 worst where fire has injured the trees." 



Mr. Carpenter said that a friend in Connecticut received five sorts of 

 wild plums from Iowa, which he has successfully grown, producing crops 

 almost as certain as apple trees, and not affected by curculio. 



Mr. Prince said that we have twenty sorts of plums that are not affected 

 by black knot. There is one purple damson that shows no sign of that 

 disease when grown side by side of the common damson that is covered 

 with knots. 



Can Brick be Made without Clay. 



Mr. R. M. Ormsbee, Porter's Corners, N. Y., says that he lives eight or 

 nine miles from where any good beds of clay exist for brickmaking, and 

 wants to know if brick can be made without clay ? There is sand, gravel 

 and sandy loam in his neighborhood. 



Mr. Solon Robinson. — In The Semi-weekly Tribune of Dec. 18, there is a 

 letter of mine, which describes how concrete brick are made, at Vineland, 

 N. J., of lime, gravel and loam, and I presume that the same kind could be 

 made in this gentleman's locality. 



Prof. Mapes. — These bricks are used without burning. Burnt brick can- 

 not be made without clay, for that is the philosophy of all manufacturers 

 of this kind. Burning tlie moistened and well-tempered clay changes it to 

 a hard, stony substance. One of the secrets of making concrete is to use 

 a very small quantity of lime, and thoroughly incorporate it by working, 

 and the impure limestone, such as Rosendale cement is made of, would be 

 better than pure lime for concrete work. Too much lime is generally used 

 in mason's mortar. To make first rate mortar the mass should be worked 

 and pounded like putty. Sometimes mortar is made a year before being 

 nsed. 



Indian Hemp. 



Mr. Nathan Harding, Lakeville, N.Y., says that Indian hemp will make 

 as handsome thread as flax; that it is perennial, and that its roots spread 

 like Ai<depias tuberosa, and that it grows upon wet land five feet high, and 

 he believes it might be made a profitable plant for cultivation. 



An Appeal for the Forests. 



Mr. Jesse Harrington Medina, Ohio, makes an earnest appeals to Ameri- 

 cans to save forest trees from total annihilation. He says : 



"The reports of the proceedings of the Farmer's Club as published in the 

 Tribune is worth twice the cost of the paper. I have been greatly benefited 

 and gratified in reading the instructions relative to cultivating trees and 

 vines. Suffer me to plead a little for the forest. No man who loves his 



