A location for a railroad line from Portland to Jacksonville is eminently practicable, and the citizens of the Willamette will be blind to their own interests if they do not so move in the matter so as to secure to themselves the advantages of the ample provisions made in the Pacific Railroad Bill for a connection between Portland and Sacramento; but south from Jacksonville there will be a severe problem for the engineers to solve, both in the shape of grades and tunnels. The Calapooia range will present an easy problem for solution; but the Scott's [Siskiyou?] and Trinity mountains will not be easily handled. They are high, broad, and broken, and no railroad line can be laid across or through them, except at most enormous cost. But that it is practicable, and will in time be built, I have no doubt. But my views relative to this location as a branch of the Pacific Railroad have been more than confirmed by a detailed view of its geography, and I still insist that a branch of the Pacific Railroad that will benefit Oregon and Washington as such can only be found by tapping the main trunk at or near Fort Laramie, and coming into the Columbia at or near the mouth of Snake River; and thence using the main Columbia to such a point whence freight can be shipped to and across the ocean. I made special inquiries relative to the depth of snow across the Calapooia, Scott's and Trinity mountains during the past winter, and learned that not less than eight feet fell upon these mountains; still the stage coach passed these mountains every day until the freshet suspended the travel; which was for the period of six weeks. The Scott's and Trinity mountains are higher than any mountains crossed by my road from Walla Walla to Fort Benton; and knowing that the question of snow with us is no more difficult than that met and overcome on this and other lines, I am sanguine to believe that a mail line from Fort Laramie to Walla Walla will prove eventually practicable. But the _experimentum crucis_, that will leave no lingering doubt even with the most uncompromising cavalier, will be afforded us, I trust, during the next twelve months; and that will deliver at our doors in Walla Walla the mails direct from Saint Louis in fifteen days. I am but too anxious that this last crowning success should be afforded us; not only to give us increased mail facilities for the present, but to awaken a practical attention to that region where the _isothermal_ and _isochimal_ lines have for ages past presented, and do still continue to present, to us meteorological phases as wonderful in their nature as they are destined to prove useful in their future results.