The Steamboat Combination.--The existence of such a combination amongst the owners of the steamboats engaged in the Lake trade, has been a great detriment to the Western country for the last two years, and had the effect to greatly retard eastern emigration. Combinations in steamboats, like banking corporations of late years, are only gone into for the sake of being the better able to shave and defraud the public. At least, so the public generally consider them, and avoid when they can without too much inconvenience to themselves, the high rates of fare and impositions which they expect to be subjected to on the Lakes, by taking some other route. But for this cause we believe, that nearly the whole of the southern travel, by the way of the Mississippi, would pass through the Lakes during the summer months. It is undoubtedly the most pleasant and agreeable route that can be taken. It looks to us like short sighted policy on the part of the boat owners, as well as highly injurious to the West. There is no complaint made, we believe, against the boats engaged in the Upper Lake trade this season, with the exception of two, the Great Western and the Chesapeake -- and they have generally, obliging and attentive offices. The Illinois, Madison, Missouri and Bunker Hill, have, when they came into our Bay, evinced a spirit of accommodation, and a disposition to afford every facility in the landing, and receiving freight and passengers. But we have heard great complaint against the Western and Chesapeake for the want of accommodation manifested by their officers to our citizens, and to strangers, many of whom have been left by reason of the short stops made by them. A little competition would do such men as Capt's Walker and Howe good, and learn them to show a little more accommodation to Milwaukie. We trust that our citizens will patronize such boats only as shew a spirit of accommodation to them. They will soon learn to drop their anchors and allow passengers time to get to, and from them, especially in fair weather.