When Nature formed the Grand River and Saginaw valleys, she seems to have been engaged in an animated contest with herself. The developments are such as to warrant the conviction that other and perhaps equally valuable salt springs lie hidden in the intervening space between those valleys. These and other discoveries plainly indicate that the employment of a large amount of capital in developing the latent resources of Michigan would amply "pay." The inexhaustible plaster beds of Grand Rapids constitute one of the prime sources of prosperity of that enterprising metropolis of the Grand River Delta. Our whole State has also a great interest in the trade, the material being, it is admitted, a better fertilizer than the imported article. CHAPTER XV. Desirableness of a trip to the Lakes -- Routes of travel -- Interesting localities -- Scenery -- Southern coast -- Portage Lake -- Dr. Houghton -- Ontonagon -- Apostles' Islands -- Return trip -- Points of interest -- St. Mary's River -- Lake St. George -- Point de Tour -- Lake Michigan -- Points of interest -- Chicago. A trip to the northern lakes, for variety and beauty of scenery to such as are seeking enjoyment and pleasure, possesses advantages over every other route of travel in the United States, and with the exception of the works of art and the classical associations of the old world, is unsurpassed by any on the globe. To such as are in quest of health, no comparison can be instituted, as it has been demonstrated that the Northwest, especially in the region of the lakes, possesses the most invigorating climate in the world. A reference to the mortuary tables removes all doubt on this point. In the town of Marquette, on Lake Superior, containing a population of over three thousand, there were during the last year but eight deaths, and only a portion of that number was from disease.