There is no stronger evidence of the practical tendency of the minds of American inventors, than that exhibited in the oonstant devising and -construction of machinery to fabricate articles of universal demand and use. It is not more than twenty year since clocks were exclusively furnished to us by European countries, and their manufacture here was almost unknown. Now, thanks to the inventive genius of our own mechanics, they are daily manufactured by thousands, through the instrumentality of machinery, which enables them to be constructed not only in a much superior and correct manner, but at one-twentieth the price originally demanded for them when manufactured by manual labor. The most ingenious machinery is now in operation for this purpose, in a few factories in the Eastern States, which not only supply all our own States with the most beautiful and correct household timepieces, but for upwards of twelva years past have been annually exporting them in large numbers to every corner of the world. We some time since gave a casual notice of an extensive establishment in Waltham, Mass., for the manufacture of watches, upon the same principle, and by somewhat analogous machinery to that employed for the manufacture of clocks. Since that period this latter trade has been increasing in such a marked degree, as to leave no doubt that it will eventually rival, if not surpass, that of clock-making by machinery. The watchmaking works were commenced by men of reputation and ripe judgment, who invested a large capital in the construction of the most delicate, costly, and ingenious machinery, to form and complete the respective parts of the watch; hence they are particularly careful that all the work leaving their hands shall be of the most perfect character. At the commencement of the enterprise,they very properly possessed themselves of all the available inventive ability and skill of the best mechanics, in simplifying the works of the watch and the construction of machinery for their fabrication. Dies of the most exquisitely delicate formation are employed for cutting the various wheels, as well as the other intricate parts, and lathes and polishing wheels for reducing the pivot jewels to the proper size, and giving them the proper finish. And while the simplicity observed in the construction of the watch.lessens its liability to stop or otherwise get out of order, any cause of disarrangement is more easily detected, and the expense attending the repairs of more complicated watches avoided. It is believed that a Waltham watch is worth double the price of many of the imported watches made by hand. In the event of any part of one getting out of order—as, for example, if a wheel or other part should break—it is only necessary to enclose the broken part to the factory through the mail, and by return post a perfect duplicate can be transmitted. The original intention of the gentlemen engaged in this important undertaking was to make a perfect and cheap article, and thus to establish it upon a firm basis ; and our impression is, that this marked innovation of Yankee ingenuity upon the cheap labor of Geneva and other parts of Europe, will eventually result in the entire destruction of their export trade.