In the rapid movements of the Army of the Potomac these lines aided materially in establishing that communication between the scattered army corps which afterward rendered their sudden concentration before the enemy at Gettysburg possible.

The siege of Charleston afforded a fair field for the use of these trains. They have been skillfully handled by the detachment of the corps there serving. The reports at this office would indicate their employment as a success. For the hundred days of the siege now past, the communications with General Gillmore's troops in the trenches and in reserve have been kept with field lines, pushed forward and maintained under the fire of the enemy, and advanced with the advance of our troops to the farthest point reached by our forces at Fort Gregg.

At the siege of Fort Wagner the lines were so close to the enemy that his sharpshooters fired at the wire. It was repeatedly cut by pieces of shell. The wire was mended by soldiers of the corps, who were exposed to a dangerous fire of grape. One of the first instances on record of a soldier actually wounded at the instrument is that of Sergeant Emerson, of the Signal Corps, who was severely wounded by a shell, which destroyed in its explosion the splinter-proof in which he has working in the parallel, and buried himself and Lieutenant C. F. Cross, the officer in charge, some feet in depots in sand. These instances are mentioned as illustrative of the mode in which the portable lines of the corps should be worked. Their use has been here, as elsewhere, supplementary to the use of the flags and the other aerial signals by which the corps keeps its communications.

Thus, while these communications existed in the trenches in front of Charleston constant communication was kept with the fleet in the bay and the river on both flanks of the army, and from signal towers with different division of the forces. The portable lines, as can be judged by the dated at which their distribution commenced, have been so in use in the different departments that the results cannot at present be properly judges. There are only general reports from the Departments of North Carolina and Virginia, the Department of the Gulf and of the Tennessee. There are trains in the field having a part in the operations in each of these departments. The general tenor of the reports indicates a fair success.

A summary report in reference to the average working of this apparatus for the past year has been called for and will be laid before the Department. There have been, of course, as it was reasonable to expect, accidents, sometimes incompetent management, and such errors as were to be anticipated at the commencement and in the early progress of such a service. The service rendered, however, has not failed to be of very essential value. The equipment of the trains, while it can be improved, seems to be in its general character proper for the purposes intended, whilst the material carried by them has been useful.

Questions have arisen as to the distance at which lines can be worked by the instruments carried by these trains, and also as to the durability of the instruments. I am of the opinion that with proper care the dial instrument will be sufficiently durable for the purpose to wh of working can be increased with improved instruments or proper modifications of the apparatus. The expense attending this service compared with the results it is capable of accomplishing . With proper organization and man