Yours, in haste, A. C. HAMLIN, M. D. * * * * * 64 Madison Avenue, New York, Aug. 23, 1867. My Dear Friend. I have just read your Lectures on "Ventilation," and I am very much obliged to you for the entertainment and instruction they have given me. You have very happily hit upon a style which is neither flippant nor dry. I am sure the lectures will be read, and if read, they will do a great deal of good. I have all my life been talking and writing in this direction, imploring the people to take less medicine and more pure air; and I feel truly grateful for the help your strong shoulders have given me in what has thus far proved to be a labor of Hercules. Your particular method of ventilating buildings I had many opportunities of proving while I was Medical Inspector U. S. A., and I assure you that no plan was ever more simple and inexpensive--none could have been more effective. Indeed, I may say that I never knew it to fail. To you, therefore, I fully believe the country is indebted for the lives of many thousands of men. With sentiments of esteem, I remain yours truly, FRANK H. HAMILTON, M. D., Prof. Principles of Surgery, Military Surgery, Hygiene, &c., Bellevue Hospital Medical College, N. Y. Author of Work on Fractures and Dislocations, Treatise on Military Surgery, &c. L. W. LEEDS, Esq. * * * * * Office of the Metropolitan Board of Health, No. 301 Mott Street, New York, August 26th, 1867. Friend Leeds. Your Lectures on Ventilation have given me much pleasure, and have renewed my confidence in the utility of popular instruction upon the subject. I heartily thank you for the thoughtful care with which you have set forth all the essential principles of ventilation, in language so free from technical words, and so full of plain and homely illustration, that even an uneducated reader can fully understand all you have written. The good Dr. D. Boswell Reid, Dr. Wyman and myself had each attempted to use such a style of explanation and instruction; but you have far excelled us all.