He returned to Fort Snelling in October, and remained there for some time, studying Dakota. He became the guest of Mr. Henry H. Sibley at his home in Mendota for the winter. General Sibley, in speaking of him, says: "A portion of the winter following was spent by him at my house, and it is hardly necessary to state that I found in him a most instructive companion. His devotion to his studies was intense and unremitting, and I frequently expostulated with him upon his imprudence in thus overtasking the strength of his delicate frame, but without effect." Nicollet went to Washington after his tour of 1836-37, and was honored with a commission from the United States government to make further explorations, and John C. Fremont was detailed as his assistant. Under his new appointment, Nicollet and his assistant went up the Missouri in a steamboat to Fort Pierre; thence he traveled through the interior of Minnesota, visiting the Red Pipestone quarry, Devil's lake, and other important localities. On this tour he made a map of the country, which was the first reliable and accurate one made, which, together with his astronomical observations, were invaluable to the country. His name has been perpetuated by giving it to one of Minnesota's principal counties. MISSIONS. The missionary period is one full of interest in the history of the State of Minnesota. The devoted people who sacrifice all the pleasures and luxuries of life to spread the gospel of Christianity among the Indians are deserving of all praise, no matter whether success or failure attends their efforts. The Dakotas and Chippewas were not neglected in this respect. The Catholics were among them at a very early day, and strove to convert them to Christianity. These worthy men were generally French priests and daring explorers, but for some reason, whether it was want of permanent support or an individual desire to rove, I am unable to say, they did not succeed in founding any missions of a lasting character among the Dakotas before the advent of white settlement. The devout Romanist, Shea, in his interesting history of Catholic missions, speaking of the Dakotas, remarks that "Father Menard had projected a Sioux mission, Marquette, Allouez, Druillettes, all entertained hopes of realizing it, and had some intercourse with that nation, but none of them ever succeeded in establishing a mission." Their work, however, was only postponed, for at a later date they gained and maintained a lasting foothold.