As to exercise, I take abundance; perform all my practice (except in the winter) on horseback, and find this the very best kind of exercise for me. I seldom eat oftener than at intervals of six hours, and am apt to eat too much--have at various times attempted Don Cornaro's method of weighing food, but have found it rather dry business, probably on account of its conflicting with my appetite; but I actually find that my stomach does not bear watching at all well. My brother continues to practice nearly total abstinence from animal food. I have seen him but once in two and a half years, but learn his health has greatly improved, so that he was able to take charge of a high school in the fall of 1836, of an academy in the spring of the present year, and also again this fall. During his vacation last July, he took a tour into the interior of Worcester county, Mass., and came home entirely on foot by way of the Notch of the White Hills, traveling nearly three hundred miles. This speaks something in favor of rigid abstinence--as when he commenced this regimen he was extremely low. Yours sincerely, H. A. BARROWS. LETTER II.--FROM DR. JOHN M. B. HARDEN. GEORGIA, Liberty Co., Oct. 19, 1837. DEAR SIR,--I stated in my letter to Dr. North, if I recollect correctly, that the use of animal food was resumed in consequence of a protracted indisposition brought on, _as was supposed_, by the inhalation of arseniuretted hydrogen gas. The gentleman had begun to recover some time previously; and in a short time after he commenced the use of the animal food, he was restored to his usual health. He has continued the use of it ever since to the same extent as in the former part of his life. He has lately passed his fifty-fifth year, and is now in the enjoyment of as good health as he has ever known. I know of a gentleman in an adjoining county, who with his lady has been living for some time past on a purely vegetable diet. They have not continued it long enough, however, to make the experiment a fair one.