In 1894 yet two more additions were made to the list of Atlantic cables--one on behalf of the Commercial Cable Company, and the other for the "Anglo-American" Company. The new "Commercial" line was constructed and laid by Messrs. Siemens Brothers, and the "Anglo" cable by the Telegraph Construction Company. Fig. 43 shows the type adopted for the deepest water of the latter, and Fig. 44 that for the shore ends. Here the wires, besides being of a very large gauge, are applied with an extremely short lay (hence the elliptic appearance, though circular in reality), in order to increase the weight of iron, and thereby avoid shifting and abrasion. This type is now in constant use where rocks, ice-floes, strong currents, or rough weather are experienced. Special arrangements were made in the design of both these cables to meet the requirements of increased speed. Since the successful application to submarine cables of various modifications of Wheatstone's automatic transmitter, the limit to the speed attainable only depends, practically speaking, upon the type of cable employed. On these principles the core of the new "Commercial" cable was composed of a copper conductor weighing 500 pounds per nautical mile, covered with a gutta-percha insulating-sheath weighing 320 pounds per nautical mile, while the new "Anglo" has a core with conductor weighing 650 pounds per nautical mile, and gutta-percha insulator 400 pounds per nautical mile, involving a completed cable (main type) nearly double the weight of previous corresponding lines. [Illustration: FIG. 43.--Anglo-American Atlantic Cable (1894): deep-sea type.] [Illustration: FIG. 44.--Shore-end of the 1894 "Anglo" Cable. Reduced size.] The actual speed obtained by automatic transmission with the latter cable is as high as forty-seven (or even up to fifty) five-letter words per minute. On the previous, lighter, Atlantic cores twenty-five to twenty-eight words per minute was the usual maximum speed attainable; the former, say, by average transmission and average receiving, and the latter by automatic transmission--other circumstances corresponding. Practically all submarine cables between important points--and certainly all those across the Atlantic--are now "duplexed"--a system of electrical working (instituted by Messrs. Muirhead in 1875) which enables messages to be sent in both directions at the same time. The result of this is nowadays to practically double the carrying capacity and earning power of the line, the effective speed in either direction remaining virtually the same as in "simplex" working, provided the cable is in good condition.[73] The armor of this cable (Fig. 43) is also a good example of present-day practise, each wire (usually covered with compounded tape) butting against the next; this is found to be the most durable form for a deep-sea cable.