would call special attention; also to a letter following of April 1 from the present aeronauts in the Army of the Potomac:
HEADQUARTERS AERONAUTICS DEPARTMENT,
Camp near Falmouth, Va., March 30, 1863.
Brigadier General S. WILLIAMS,
Assistant Adjutant-General, Army of the Potomac:
GENERAL: on the 21st of this month I received from you an article setting forth a new plan for operating balloons for military purposes, proposed by a Mr. B. Englend, and referred to me for an expression of opinion and report. In consequence, however, of my time being occupied during the past week in Washington before the Committee of Congress on the Conduct of the War, I have not been able to make a report until now.
In examining the papers I find many mistatements concerning the present balloon operations, which in justice to myself and those connected with this department, I feel in duty bound to set right.
First, then, in comparing the two methods, he states that "the time required to inflate a balloon by the present mode is fifteen, hours," when in fact it never required over three hours and fifteen minutes, and since adding my last improvements Mr. Allen, one of my assistants, informs me that the gas now makes in two hours and thirty minutes instead of fifteen hours as represented.
Second. He states that the cost of inflating now for a simple inflation is $400, when the actual cost is only about $60 now; and when the iron (which we now obtain free of cost at the Washington Navy-Yard) had to be purchased, the cost was then in the neighborhood of $75, which, when divided into fourteen (the number of days the balloons will retain their power, on the average), the cost per day for gas will be about $5.30. Of course this does not include contingent expenses.
Third. Mr. Englend states that it now requires 12,000 pounds of acid and iron for a single inflation, when, in fact, that amount will keep two balloons inflated from three to four weeks.
Fourth. He states that it now requires twelve or fourteen wagons, when the facts are that it never did require over seven wagons to haul four balloons and appendages and material to keep them inflated, and all camp and garrison equipage for the whole aeronautics corps.
Now that I have made the above corrections, I will give my opinion (as I am ordered to do so) of the relative advantages between the method proposed and the one now employed.
First. According to the statement of Mr. Englend, it requires a bulk of 68,000 cubic feet to lift the same weight that now requires 15,000 cubic feet, much less than a quarter of the capacity of the balloon which he proposes. After figuring the weight of the appendages, which he puts down at 750 pounds, he then has left 250 pounds ascensive power. Now, considering that nine-tenths of the ascensions now made require an ascensive power of 400 to 600 pounds in order to counteract the force of the wind against the side of a balloon, it is certain that with a bulk more than four times as large and weight and with less than a quarter of the power, it could not ascend at all; or, in other words, when the balloon of 15,000 cubic feet capacity lifting 1,000 pounds, with weight of apparatus and two persons, between 400 and 500 pounds, can ascend from 1,000 to 2,000 feet, the balloon of 68,000 feet capacity and weighing 750 pounds, with a lifting power of 1,000 could not be held by fifty men against the wind, and would be blown to the earth.
Second. I should say that it would be impossible to tow from place to place a balloon of the kind last mentioned; therefore should two ascensions be required at different points in one day (as is often the case, in order to make a full and correct report), the balloon would have to be inflated at each point, which would be another impossibility, and would involve the expense of $250, according to the cost set down for each inflation. Besides, the constant handling of the machinery must necessarily soon wear it out.
I would here take occasion to say that the balloons now in service have been in use for nearly two years; have been inflated from one to two months without changing the gas; have stood the storms of two winters, and are kept constantly ready to ascend at five minutes" notice (whenever the weather will admit), and ascend four times higher than ever was done (by ropes) before. These are circumstances which history afford no parallel in any country. Notwithstanding all this, I would respectfully recommend that Mr. Englend be permitted to try his experiments in the field beside the present balloon operations, in order to com-