Though large countries within our Union are covered with the sugar maple, as heavily as can be conceived, and that this tree yields a sugar equal to the best from the cane, yields it in great quantity, with no other labor than what the women and girls can bestow, who attend to the drawing off and boiling the liquor, and the trees when skilfully tapped will last a great number of years, yet the ease with which we had formerly got cane sugar, had prevented our attending to this resource. Late difficulties in the sugar trade have excited attention to our sugar trees, and it seems fully believed by judicious persons, that we cannot only supply our own demand, but make for exportation. I will send you a sample of it, if I can find a conveyance without passing it through the expensive one of the post. What a blessing to substitute a sugar which requires only the labor of children, for that which is said to render the slavery of the blacks necessary. An act of Congress authorizing the issuing of patents for new discoveries has given a spring to invention beyond my conception. Being an instrument in granting the patents, I am acquainted with their discoveries. Many of them indeed are trifling, but there are some of great consequence, which have been proved by practice, and others which, if they stand the same proof, will produce great effect. Yesterday the man who built the famous bridge from Boston to Charlestown, was with me, asking a patent for a pile engine of his own construction. He communicated to me another fact, of which he makes no secret, and it is important. He was formerly concerned in ship building, but for thirty years past has been a bridge builder. He had early in life observed, on examining worm-eaten ships, that the worms never eat within the seams where the corking chisel enters, and the oil, &c. He had observed that the whaling vessels would be eaten to a honey-comb, except a little above and below water, where the whale is brought in contact with the vessel, and lies beating against it till it is cut up. A plank lying under water at a mill of his had been obliged to be removed annually, because eaten up by the worms in the course of the year. At length a plank was accidentally put down which for some purpose had been thoroughly impregnated with oil. It remained seven years without being affected. Hence he took the idea of impregnating the timbers of his bridges thoroughly with oil, by heating the timber as deeply as possible, and doing it well in that state with the liver oil of the codfish. He has practiced this for thirty years, and there is no instance of the worm attacking his timbers, while those in neighboring places are immediately destroyed. He has used the liver oil of the cod, because very thick, and therefore, as he supposes, more permanent in its effect. He supposes some other oils might do, but cannot speak of them experimentally. He says there will be no difficulty in heating the planks of a ship after they are