From the National Archives, RG 109, Ch. 6, Vol. 364, “Letters Sent & Received, Medical Director’s Office, 1864-65.” p. 166

Medical Director’s Office 29 July ‘64

Sir

I would suggest that you draw the necessary Hospl funds previous to rendering the monthly abstract, to enable you to buy mules or horses sufficient to supply an additional ambulance for each Division of the Hospls under your Charge. Considering the probable wants of others in the Department, and the future wants of Chimborazo, you will not turn in any excess of Hospital fund to the Treasury this month, but draw it and turn it over to me, in accordance with Par. 10(?) G.O. No. 6 A. & I. G. O. ’64.

Respectfully &c.
Wm. A. Carrington
Medical Director

Surg. McCaw