the four companies of engineer soldiers now authorized by law be filled up to the maximum. This, I believe, may be done by transfers from the volunteer force now assembled near this city.

Let us limit the force here to one hundred regiments, and say we want 500 men. This will call for 5 men from each regiment on an average. If the order inviting or authorizing such transfers should limit the number to be taken from each regiment, without the consent of the colonel, to 10, I believe the four engineer companies may at once be filled, and after an explanation of the absolute necessity for such troops all opposition on the part of regimental commanders would be silenced, or could at least be met by silence. These men should not be taken at random. Only such as are qualified by previous pursuits to make engineer soldiers should be transferred.

This would soon give us a small body of men, but by no means the number that the emergency requires. Without the authority of law to raise such troops, and without the power to raise the pay so as to command the services of good mechanics, I see no other way to supply them than by taking two or three of our best volunteer regiments, detaching them from the line of the Army, and instructing them as best we may with the limited number of officers who have made this a specialty in the duties of engineer troops. I understand that there have been several volunteer regiments organized with a view of being converted into engineer troops. These will probably be the regiments to be selected.

We shall have roads and railroads to build and repair; telegraph lines to put up; bridges to construct and destroy; and fortifications to build, to defend, and reduce. Except in the construction of military bridges, and the investment and reduction of fortified places, it may be hoped with some degree of confidence that after a little experience our engineer troop so obtained would soon become proficient. These two subjects require study. Each of them is a specialty, and I confess that my ideas are not sufficiently matured to enable me to give clear and distinct views on the subject-to direct your attention to something that is fixed and will not require alteration hereafter.

As to bridges, we shall want several equipages. We can therefore afford to begin at the beginning. The India-rubber pontoon bridge that we have ought to be tried, and, if necessary, perfected. Our engineer troops, if a proper proportion of them are sailors, will soon learn to use it. A few trestle bridges may be made, using, say, for one bridge, the common trestle; for another, the Birago trestle; and for another, the Birago trestle and pontoon combined. I made the canvas boats that Lieutenant Ives, of the Topographical Engineers, used in his expedition on the Colorado River. Before letting them go out of my hands I used them on several occasions. I was much pleased with them, and Lieutenant Ives afterwards informed me that they answered his purpose admirably. I confess myself favorably impressed with this boat. A bridge train with these boats for pontoons could be very rapidly made.

We have 100 corrugated-iron wagon bodies now here in the Quartermaster's Department. This gives us the foundation for still another bridge, which can be readily made. These wagon bodies, if they are as good as the testimonials in relation to them seem to imply, will become very useful. By themselves each one of them is a large boat, and, if properly made, they ought together to be easily converted into a bridge.

I am very favorably impressed with Murphy's suspension bridge, a