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upon the poles of the line. This monster form of magnet wascontinued for a short time, and replaced by another less in size,devised by Professor Charles G. Page. These latter remainedin the service until substituted by some of the size now in use,which had been purchased by Professor Morse in France in theyear 1845.
INVENTION OF THE LOCAL CIRCUIT.
In regard to the invention of the local circuit, ProfessorMorse deposed, viz.:
“I further state, that the combination of machinery in con-structing my telegraph as put in operation in 1844, was differ-ent from that originally contemplated and described in my firstpatent in the following respects, viz.: The combined circuits ofmy first patent, were the combination of two or more circuitsas links in a main line for the purpose of renewing the powerand propelling forward, indefinitely, the electric current, insuch volume as to render the power more available at the dis-tant point, and to charge an electro-magnet with sufficientmagnetic force to work a register or move the lever of a relaymagnet, suggested by the probability indicated by my ownexperiments and the experiments of scientific men, that suffi-cient magnetic power could not be obtained from the electriccurrent through a very long circuit to make a mark of any sort.
This difficulty the undersigned proposed to obviate by meansof two or more circuits, each with a battery, coupled togetherand broken and closed by means of the same principles as thereceiving magnet now used ; these links of one main line areto be made so short as to secure the necessary magnetic power.
The register was to be placed, not in a short circuit, as nowarranged, but on a link in the main line. But this arrange-ment was liable to the practical inconvenience that it wouldalways require two lines of wire, both always in order; be-cause the receiving magnet would work only in one direction.
While preparing to build the line from Washington to Balti more , I ascertained, by experiment upon one hundred andsixty miles of insulated wire, and, sometime previously, uponthirty-three miles of wire, that magnetic power sufficient tomove a metallic lever could be obtained from the electric cur-rent of a circuit of indefinite length, and that there was nonecessity for combining two or more circuits together for thepurpose of renewing the power at short intervals on the mainline.
I then devised the present combination, which enables meto work the same wire both ways, dispensing with one of