have sufficed (in the absence of any appreciable return current, as in subterranean lines,) for all ordinary conducting powers. I have tried, with Mr. Statham, the Manager of the Gutta Percha Company, some important experiments on the conducting ratio of different sizes of gutta percha coated-wire, which show a considerable difference in conducting power of copper wire, leading me to the decision that, for any line of a length above one hundred miles, it is not expedient to use a size less than No. 16 copper wire (Birmingham wire guage). I extract a few notes of our experiments on Nos. 18 and 16, as clearly showing the difference. Fifty miles of No. 16, and fifty miles of No. 18, tested for continuity with a Galvanometer. The loss of conducting power appears, therefore, to be more than proportionate to the different area of metal. Mr. Statham, who went to considerable pains in investigating the ratio of conductibility, and insulated many miles of various sizes, practically to demonstrate the differences, has made a very good wire for short distances, by which a saving may be effected in such lengths of underground lines, which he calls No. 7 Gutta Percha Covered Wire, the copper wire being 18 --the gutta percha being double covering, but not so thick. Answer 77th-MAGNETO ELECTRICITY.-I am naturally strongly in favor of the use of magneto-electricity. Its economy is undoubtedly the most prominent feature. A pair of magnets costing at Sheffield 30s. and perhaps 40s. to 45s. (according to the finish bestowed on the instrument,) by the time they are fixed and ready for use, will send a strong current on a well insulated suspended line for above 200 miles, and on an underground wire above a hundred. (I have had signals, but only weak ones, through 250 miles of underground wires with the class of instruments I am speaking of) while the six twelve-cell trough battery used in this country, which would be necessary to perform the same work, would cost £7 10s., besides the constant expense of renewal, &c. A magnet, if the keepers are put on when the instrument is not in use, will retain its magnetizm for an indefinite time. I have not as yet had to re-magnetize any of our sending magnets, though we have instruments that have been in use since our incorporation in 1852, and some since the exhibition in 1851, where our apparatus carried off the highest medal the jury could allot. I cannot speak as to what length of circuit magneto-electricity can be used, as I have not as yet tried with magnets of great power, beyond those we use daily. We work the longest circuit that is daily worked in Eng. land-from Liverpool to Belfast and Dublin, an underground line, which, with a pole line would be equal, at least, to 800 miles, though I doubt if we could put a current of such power into any pole line, unless in very dry weather. The magnets here used, are the large horse-shoe compound magnets you have seen in our offices, about 15 inches from the poles to the back, about 5 inches in height, made of 12 plates, in breadth about 1 inches. I have spoken with these for experiment through 530 miles of underground wire; but for our arrange ment of circuits it would be unnecessary, and inconvenient, as we should have to lay more wires so as to connect up long direct circuits, which would be very little used. These magnets cost nearly £7 each. Answer 78th.--We have no mode in use, because it is not adapted to our system, the magnetic current we send being sufficiently long for our purposes. I do not see much difficulty in keeping up a continuous current. Wheatstone patented one some years since, but it was complicated and comprised six compound magnets for each wire. A simple reverser, which should change exactly as the coils. changed their polarity, similar to that used by Billant, and a close arrangement of the poles of the permanent magnet, are the chief points. By rotating a disc or plate, with coils on its axis between the poles, perhaps an equal current might be maintained. I have not given much attention to the subject, as we do not use continuous currents here, and can obtain sufficient duration of the effects of the movement of a pair of coils for about 30 degress in the face of a permanent magnet, by having the receiving coils and their cores so arranged as to retain the residual magnetism until another current is sent. Answer 79th. We do not use our wires continuously charged with electricity. Answer 80th. I do not know of any practically, from having had no experience at all in the use of continuous currents. Glancing at the subject, I should think there must be some inconvenience wherever an iron core is used in the receiving coils by the residual magnetism retaining the keeper or magnet. This would be increased in an underground line, where the return current would follow so quickly on any break of current, as to make any rapid sending impossible. Is not the expense of maintaining battery much increased by their more frequent operation? Answer 81st-SUBMARINE TELEGRAPHS.-I like the plan most generally adopted the best--that of covering the gutta percha wires first with tarred hemp, and afterwards with strong iron wires wound spirally round the rope. They have been made in England chiefly by Newall, of Gateshead. The cost varies very much of course, according to the size of wires used, &c. Answer 82d.-I do not think there is. It weakens the rope, and in manufacturing is liable to injure the gutta percha wires by scaling, &c. We lost a galvanized rope between Portpatrick and Donaghadee in October, 1852, which was entirely recovered afterwards. A new one, ungalvanized, was laid in May, 1853 --the first successful attempt to connect England to Ireland after three failures by other companies and ourselves. Answers 83d to 92d.-I have either been unable to give reliable information on the subjects, or cannot just now go into them fully, and collect estimates. I shall be happy to do so hereafter, if you have not obtained full particulars from others. Answer 93d--INSULATED WIRES ON POLES.-Gutta Percha wire has not been used in England upon poles. For my own. part, I consider it would have all the disadvantages of both the overground and underground systems, with few of the merits of either. I speak of our abandoning gutta percha pole insula tors under No. 4. Answer 94th-COMBINING CIRCUITS.-We have no circuit with anything like that number of stations, so I cannot speak by experience; but I have no doubt if our present instruments could not overcome so great a resistance as that number of receiving coils in a long circuit would present, that apparatus could, without difficulty, be made that would be sufficient. We have no arrangement exactly such as you mention; but, at all our junctions we have switches for turning the branches into direct communication with the main lines. Answer 95th-GALVANIC BATTERIES.-Trough batteries after Wollaston and Cruikshank's plans. Mr. Cooke modified them, and introduced the use of sand in the cells, which equalized the action, and made the batteries more convenient for carriage and use in offices. I speak of the first working telegraph-not experiments. Answers 96th and 97th-FIRST ENGLISH TELEGRAPH.-Cooke and Wheatstone's Needle Telegraph. That with 5 needles, used on one or two lines at first-(the Norwich and Slough lines the only ones I remember at present)-but were shortly afterwards changed for the double needle as more convenient and economical. The first line-the Great Western to Slough-was fixed in 1839. It was erected on short standards, the wires being laid in a trough carried on them. It was worked a long time, but has since been changed for the suspended wire sys tem. Its chief use was for the railway company's affairs, and partly for commercial business. Other lines followed rapidly after this-among the foremost, the Southwestern to Southampton, Gosport, Portsmouth, &c., with wires for government use in the Admiralty Department. DIRECTIONS FOR INSULATING JOINTS IN GUTTA PERCHA COVERED ELECTRIC TELEGRAPH WIRE. HAVE in readiness a few strips about inch broad, of very thin Gutta Percha Sheet, also a little warm Gutta Percha about inch thick, one or two hot tools, and a spirit lamp. Remove the Gutta Percha covering from along the wire no further than may be necessary for making the joint in the wire. Having joined the wire, warm gently with the spirit lamp the bare wire and joint, and the Gutta Percha near to it; taper the Gutta Percha over the bare wire until the ends meet; warm this, and immediately apply one of the strips of thin sheet in a spiral direction over it. Press this covering well on until cool; then, with the spirit lamp, carefully warm the surface, and proceed as before to put on a second strip of the thin sheet, observing to wrap it in a direction reverse from the first strip, always making the commencement and termination of these coverings to overwrap the previous one. It is safer to perform this operation a third time. Next, take a piece of the warm inch sheet, and cover over the coats of thin sheet, again overwrapping the original covering of Gutta Percha, which should be heated so as to ensure perfect adhesion. Press it well on as it cools, and when cold, or nearly so, finish off the joint with a warm tool, working well together the old and new material at each end. Lastly, and in general, avoid moisture, grease, or dirt, and be careful not to burn the Gutta Percha, which would prevent proper adhesion. TELEGRAPH COMPANION, DEVOTED TO THE SCIENCE AND ART OF THE MORSE AMERICAN TELEGRAPH. VOL. II. JULY, 1855. No. 3. ART I.-ELECTRIC TELEGRAPHS IN GREAT BRITAIN.-NO II. THE SCIENCE OF TELEGRAPHING-MAGNETO-ELECTRICITY-RETURN CURRENT S BY EDWARD B. BRIGHT, Secretary of the English and Irish Magnetic-Telegraph Company, Liverpool, England. (Answer to Mr. Shaffner's Questions.) Answer 44th.-RETURN CURRENTS ON SUBTERRANEAN LINES. -In the course of a long series of experiments carried on last year by my brother and myself, inquiries were instituted with reference to the speed with which the galvanic or magnetic sensation is communicated through underground wires. The result of the inquiry shows decidedly that the communication of the electric impulse through a length of 50 miles of underground gutta percha covered copper wire (16 guage) does not exceed 900 to 1000 miles per second—a speed far below that usually assigned. Reasoning upon the issue of these experiments, and those previously tried in America, I have no doubt that the speed of any description of electricity varies greatly with the peculiar conditions and nature of the conductor used, and also with the length of the conductor interposed; and that a wire suspended in the open air, especially if insulated only at points of its support, (such as in a pole line) would offer far less resistance (coeteris paribus) than a wire undergound. Submarine cables are similar, as regards electrical conditions, to subterranean lines, and the speed with which the electric impulse is communicated would be the same. I have no doubt, however, that, as Professor Wheatstone's |