From this time until the 28th of August was consumed in the construction of the first substantial war balloon ever built.

The main obstacle to the successful use of balloons still had to be overcome, namely, a portable apparatus for generating the gas had already devised a plan for this purpose, but, as I could not then obtain an order to construct the apparatus, I was obliged to inflate the balloon as formerly in Washington, and to confine its operations to that locality. At this time I received the following orders from Major Woodruff and Captain Whipple:

WASHINGTON, D. C., August 28, 1861.

Mr. LOWE,

Balloonist, Washington, D. C.:

SIR: Get the silk balloon in readiness for inflation immediately. A detail of thirty men will repair to the Columbian Armory to aid you in the inflation and transportation of the balloon.

Respectfully, yours,

I. C. WOODRUFF,

Major, Topographical Engineers.

Inclosed is an order for gas.

I. C. W.

FORT CORCORAN, August 29, 1861.

Prof. T. S. C. LOWE:

The general desires you to be here at 3 a.m. to-morrow morning to make an ascension before daybreak to examine camp-fires, and ascend again as soon as it may be light enough to watch for movements of any bodies of men. Should I not be present please write the observation and send them to me by express at Arlington.

A. W. WHIPPLE,

Captain, Topographical Engineers.

These orders were complied with, and during my observations I discovered the enemy for the first time building earth-works on Munson's Hill and Clark's Hill, and also saw their movements along the entire line. In the afternoon I moved the balloon to Ball's Cross-Roads and there took several observations, during which the enemy opened their batteries on the balloon and several shots passed by it and struck the ground beyond. These shots were the nearest to the U. S. capital that had been fired by the enemy, or have yet been, during the war.

From this time the balloon was kept in constant use and daily reports made to the commanding officers. I regret that I kept copies of but few of these, as at the time I did not consider that they would be required. Confidence in this new means of observation soon began to be manifested, and many officers made ascensions, among whom were Generals McDowell, Porter, and Martindale. On the 7th of September Major-General McClellan ascended and made an examination of the enemy's works on Munson's Hill and other points, a view of which it was impossible to obtain by any other means.

From this time to the 27th of September many alarms were given, and the troops called out in line of battle, and in every instance after an examination had been made by means of the balloon the troops were sent back to their quarters and allowed to rest without danger of being surprised.

Having only one balloon, I was necessarily compelled to lose some time to go to Washington for gas, which I invariably did, however, at night.