Our readers have several times had their attention called to the desirability of a good detachable calk for horseshoes. and we need not therefore repeat at prcsentwhat we have said upon this point. We have, however, this week to present to their consideration another improvement of this character, an engraving of which accompanies this article. The calks. A, may be formed upon a flat plate without any opening for the toe calk of the ordinary horseshoe, in which form they are made and used to some extent, but it is preferred to make the plate with an opening to admit the toe calk, B, as shown in the engraving. A tongue, C, with beveled or dovetailed sides extends back a short distance from the calk plate. Upon thistongue slides a clasp, its two lateral wings, D, being dovetailed to fit C, and having its front edge made of the proper curve to fit the toe of the shoe. It also has on its under side a flange which fits under the horseshoe when the attachment is made. A screw, E, with a counter screw and nut, F, serves to draw and hold the flange of the clasp under the inner edge of the shoe. Two curved prongs, Gr, also rise from the front of the shoe and rest against the front of the hoof. To secure a uniform bearing, to obviate all rattling, and to protect the hoof, a rubber cushion may be inserted between the prongs, G, and the hoof. The calk is easily attached or detached, and, being made of malleable cast iron,ie very cheap. The calks. A, are case-hardened, and are placed so that their angles prevent side slipping. The attachment is made upon the strongest part of the hoof. It would seem that this calk must be useful wherever roads aie icy, or whenever the toe calk on the shoe becomes worn. Patented, May 18, 1869, by W. J. Berne, whom address for further information at Cincinnati, Ohio. Telegraph Extension. Schemes for constructing and laying submarine lines of telegraph from Europe to America are being promoted with a rapidity, which is marvelous, when the magnitude of the project is considered. We understand, says Morgan's British Trade Journal, that the Ocean Telegraph Company intends to lay a new line from the southwest of Ireland to Halifax, in Nova Scotia. A new submarine system is also to be constructed between Germany and America. A concession granted by the Chancellor of the North German Confederation to certain gentlemen interested in the scheme, provides for the landing of the cable at a suitable point of the North German sea coast, and also for the erection near the place of landing of all the appliances necessary for its working. The Chancellor reserves to himself the right of selecting a point at which the cable is to be landed and connected with the telegraph lines of North Germany. He, on the other hand, will make the arrangements necessary for guarding against the malicious destruction of the cable, and for protecting it against injuries from vessels or fishing boats. The incorporators may lay the line direct without touching any other territory than those of the two countries named, or via England and Newfoundland, to any point between New York and Boston. They have the option also of constructing a new cable, or of buying any submarine cable already existing which may be available for their purpose. If the latter alternative be adopted, the Chancellor reserves to himself the right, before the purchase of the cable or cables, to cause the same to be examined with a view to test the working capacity, as well as to consider the risks to which it or they may be subjected. He also reserves the right of refusing to allow the purchase. Those to whom the concession is granted, are permitted to enter into connection with the Indo-European Telegraph Company for the interchange of messages between America and Asia or Australia. The Chancellor of the North German Confederation will promulgate the regulations regarding the transmission and exchange of cable telegrams. In order to secure connection between the new system and the telegraph lines of the interior, especially as concerns Hamburg, Bremen, and Berlin, provision will be made by the North German Bund. Regarding the messages which will be transmitted from India via England to America, future arrangements must be made with the Indo-European Company. Though the telegraphic communication will be subject to the rules laid down in the International Telegraph Convention, made at Vienna in 1868, no higher rate will be charged than that adopted by the Transatlantic telegraph companies. The construction of the cable, which, as may be conjectured, will be made after the most approved method, must, according to the conditions, be commenced within six months after the concession is granted, and the whole line must be completed within two years after the date referred to. The concession will become null and void if the working of the cable be interrupted for two years. The concession will expire after a lapse of twenty-five years unless it be resolved upon to make a new agreement. Any differences of opinion between the Chancellor of the North German Bund and the incorporators will be decided by an arbitration of three judges, to be nominated for that purpose by the civil department of the Prussian Supreme Court. In Northern Germany it may be added that the telegraphs are under the control of the Government. The concession, therefore, substantially constitutes a treaty. It is expected that the Qreat Eastern will sail on or about the 10th of November with that part of the British Indian telegraphic system which is to be laid between Aden and Bombay. It is probable that the newly designed floating telegraph stations round the coast will shortly be widely adopted, and several of them are being constructed at the present time.