The land and naval forces of the enemy seen to be will supplied with practical signal officers, and military operations on land bring our forces continually in view of hostile signal stations, of whose powers our officers ought to be able to judge. The accounts which reach us of the rebel navy at sea indicate the habitual use of those plans of signals first introduced in our armies. The officers of our navy, experienced in this war, will be able to estimate the advantages thus gained.

FIELD TELEGRAPHS.

The service of the field telegraph trains, in the hands of the corps, and making part of its equipment, has been conducted with a fair and, in some instances, a marked success in the different military departments. The liberality of the War Department has allowed a development of this branch of the duty greater than was recommended at the data of my last report, and with results which have justified the action. It remains, in my view, only to follow the path of development indicated by the experience of the past year to secure for our armies a service of field telegraphslines, so superior as to render our advance in improvements of this character as notable as those which have marked the progress of our armies in other branches of military appliances.

In my last annual report there was brought to the attention of the Department the improvement in telegraphic apparatus which the ingenuity of American artisans, stimulated by the field opened to them by this war, and the call for improved equipments for the trains for the Signal Corps of the Army, had inaugurated. The practical experience of the past year, indicating the wants of the service, and the same ingenuity constantly exercised to overcome these wants and to perfect the material, have led to developments in the art which are now attracting the attention of electricians, and which, if they fulfill the promise of their seeming, will go far to revolutionize the appliances for the transmission of signals by electricity. It is already a subject of consideration whether the appliances and the modes of generating a magneto-electric current, as first used for telegraphy in this country, in the experimental instruments made for the Signal Corps to dispense with the clumsy and untransportable voltaic battery, are not these appliances and that mode which will be necessary to transmit signals through sub-marine cables of uncommon length, as that proposed to cross the Atlantic. This is, of course, theoretical only.

The use of these instruments in the Army has led incidentally to their examination for the naval force of the United States. Their use for civil purposes attracts attention. The ingenuity of the inventor, Mr. G. W. Beardslee, of New York, turned to the subject of increasing the powers of the instruments to enable them to work at greater distances, and to apply the magneto-electric current in the same manner as generated by the field machinery, under circumstances where with the first devised instruments it was difficult or impossible, has produced, with a construction novel in this country and in Europe, a signal sounder, by which the signals transmitted are addressed to the ear. Messages transmitted by this instrument may be read as with instruments of common usage.

Experiments have been ordered with this apparatus. If, as is the opinion of the inventor, it can be used at any great distance, and