Over the Potomac there is a long wooden bridge, built upon ordinary cross-beams. I measured it, and found it to be fifteen paces broad, and one thousand nine hundred long. My paces being to the ordinary ones in the relation of four to five, it may be assumed that it is about two thousand three hundred and seventy-five paces in length. It required nineteen minutes to walk from one end to the other. Every foot-passenger pays six cents. This bridge astonishes by its length, but not at all in its execution, for it is clumsy and coarse. Many of the planks are rotten, and it is in want of repair; it has two side-walks, one of them is separated from the road by a rail. It is lighted by night with lanterns. It is provided with two drawbridges, in order to let vessels pass. It grew dark before I returned home, and was surprised at the stillness of the streets, as I scarcely met an individual.
Patents of invention are issued from the patent-office; whoever wishes to obtain a patent for an invention, is obliged to deliver a model or an accurate drawing of it. These models are exposed in an appropriate place, where they remain until the expiration of the time for which the patents are granted; they are then put into the lumber-room. Among such models, there certainly is a great number of things of little importance, as for instance, a contrivance for peeling apples; there are also ninety-six models for making nails in different ways, but some of them very remarkable. The most interesting models of machinery seemed to me to be those intended to remove mud from the bottoms of rivers, and canals, or to make them deeper. One of them consists of an ordinary steam-boat; with her they go to the spot where they are to work; arrived at the spot they cast anchor, stop the two water-wheels, and with an apparatus which is moved by the engine, draw the mud from the bottom. According to another model, the same operation can be performed by means of a draw-wheel. A great many models are intended to separate seed from cotton, to beat, spin, and weave it; none of them, however, are reputed to be superior to the known English machines.
Of steam-engines and steam-boats there are a great many models of very singular form, also steam-boats with rotatory motions; they however do not answer the purpose. I saw patterns of railways, and models of machines to draw boats from a lower canal into a higher one, by help of an inclined plane. Then two models of floating covered batteries. One of them was an oblong case, in which is fixed a steam-engine, giving to two long iron bars a rotatory motion. These bars, like two clock-hands, projecting off the deck, are intended to keep off a boarding enemy. A model to compress leaden bullets, in order to give them more weight. A great number of household and kitchen apparatus, fire-places of different descriptions, an earth-augur for seeking water, fire-engines of various kinds, a fire-proof roof, contrived by a German, several machines to make bricks, instruments by means of which, in navigating the Mississippi, trees lying under water can be taken hold of and sawed to pieces without stopping the vessel in its course, machinery to bore holes in rocks, and others to hoist rocks out of water; the machine contrived in London by Perkins to print with steel; models of book printing-presses; models for combing wool, and dressing woollen stuffs; fan-mills; leather manufacturing instruments, and among others, an instrument for splitting hides; a great number of agricultural instruments, namely, a great many ploughs for every kind of soil, invented by Germans; machines for mowing grass, for thrashing and cutting straw. Among the most important machines, I will mention one for making blocks, which is considered not to be inferior in any respect to that of Brunel, in Portsmouth, and another which renders steeping of flax unnecessary, and yet fits it after fourteen days drying to be broken and heckled. For permission to take a copy of the machine, one must pay ten dollars to the inventor. I ordered two copies; one for the Agricultural Society of Ghent, and another to present to my father. Several fine models of bridges, especially of hanging ones, among others, one of the bridges in Trenton, near Philadelphia, and another of that near Fayetteville, in North Carolina; also one of a hanging bridge, under which is suspended a canal passing over the river. Respecting arms I did not find much improvement. There was also a triangle of steel, weighing six pounds, upon which three different hammers struck, to supply the place of church bells. This ringing is said to be heard at a great distance. It has been introduced in several places to assemble the people.