Year: 1873

|sj1i How the Wonder is Worked i

 Ii The readers of the Ledger doubtless observed in the cable dispatches a no. tlce that the cable laid in 1865 had

 failed, :, at twenty minutes past twelve

 o'clock on the day before and that an electrician would leave London in the evening to {" locate the fault.''. They of

 course understood that it was the mis.

 sion of the gentleman mentioned to %

 to the shore end of the cable on the

 coast of Ireland to ascertain at what

 point of the two thousand miles of cable

 buried under the sea the cable had been

 injured or. broken. And we have no doubt some of them have wondered how

 it was possible for the electrician to

 know, or to learn, aUhere the fault or the

 break could be, considering that some

 portions of the wire were a thousand

 miles distant from his point of .observa-

 tion, and a great deal of it buried deep

 from human sight two miles beneath

 the surface of the sea. 2 Yet every part

 of that long distance, and every fathom

 of that abyss of water, are within the

 reach of the electricians S1sstrUnsentaL

 ho,ads, and within the ken of his scien-

 tifici eye. It is quite practicable for

 him to |" locate the fault'' or the break. within half mile of it's actual position. no matter where it be. 2 .s'. ss-..T s'' s

 Although these far-reaching powers

 are among the great marvels of modern science, the means and the principles through which they are exercised are among the simplest things when seen and understood. A telegraphic, wire will transmit an electro magnetic wave or current, "in proportion, to thesquare of it's diameter. The resistance to the transmission of the wave dinainishes in proportion as the square of the diame- ter is SaacTeGsed. This is one law forthe

 .. The second is that the resistance to the transmission of the wave increases in direct proportion to the length of the wire or cable over which it is sent. There two laws furnish the bases for the. electrician's observations, calcula-l tions and results. He knows, to start with, the precise amount of resistance that mile of the cable will oppose to the transmission of given Quantity of electro motive force. He has delicate and wonderful instruments, made by expert mechanics, that enable him to measure this with accuracy for half 8 mile or for ten thousand miles. Having this knowledge and these measuring in- struments, and having control of the quantity of electricity he is putting on the wire, he is able to calculate to a nicety how many miles of the cableit is transmitted over, before it encounters a greater resistance than that which is due to the length and diameter of the cable itself. At or near the end of that number of miles of cable, though it be a thousand miles from land, and two miles under the surface of the. sea, the fault or break the electrician is in search of will be found. lsgu1cas baa f

 Our readers should understand that we are not stating any mere hypothesis. This real wonder and seeming mposi- bll1ty has been accomplished again and again. The principles through which 1t is accomplished, are the discovery of one of those quiet, studious men, who plod about in their laboratories and workshops, and who are supposed by many people to be wasting their lives J about things of little practical use, but whose works, together with those of the skilled mechanics, who cooperate with them, really move the world along.

 This particular student of the laws of nature is Prof. Ohm, of Nuremburg, Germany one. of several men whose labors, like, those of Oersted and our American Prof. Henry, have made the Magnetic Telegraph possibility. The delicate and wonderful instruments by which those principles are applied, and which enable the electrician to extend his reach a. thousand. miles out to sea, and to the bottom of the ocean abyss, have been at work in one of the | most modest work shops in this city for several years. s They are the tools of a Philadelphia workman, who now leads ,he world in the manufacture of one important adjunct in ,.telegraphy-a nearly perfect ''insulator. The simple 1evice for working the ocean cable is here also. i'a tH F,'f' H.--'

 This matter has been mentioned at some length, for the benefit of frthe boys ind girls in, our public schools, who will see what grand and useful results sre accomplished by the application of he simplest principles of science, and hat they may also understand that hey need but rarely go'r beyond their 'wn city. to find whatever they may wish to know, or to understand about cience, applied to the useful purposes 'f life.--Philadelphio Ledger. .'-....s