Dear Sir: —InThe Journalof December 5 is an article by Dr. de Mello, of Rio de Janeiro, which is designed to show the identity of yellow fever and acute malaria, and which coincides with the ideas I have always entertained in reference to that subject. I was practicing medicine, from 1839 to 1846, inclusive, at the Grand Rapids of the Maumee, in Ohio. During the first three or four years of my residence there the Wabash and Erie Canal was being made. The termini were the Maumee bay in Ohio, and Evansville in the southwestern corner of Indiana, making it one of the longest canals in the world. I am not certain whether a boat ever went through the whole length of this canal. The Indiana part of this canal was abandoned a few years ago, and that portion from Terre Haute to Evansville was never used. While