In computing, the staff made use of all data of every nature which was before them, checked the judgment of the field inspector wherever any reliable data were furnished, took into account age, special notes, or costs, and, in case of any serious discrepancy in his percentage, reported to the head of the department for either a re-inspection or for a conference with the appraiser and inspector. In this department every possible safeguard was thrown around the work to insure its absolute mathematical correctness, and to guard against errors in the personal equation. _Compilation._—After the calculations were checked and completed they passed to the compilers, who arranged and classified them, and prepared the form of the final report. This consisted of a detailed list of every piece of property and every structure, with a short description and specification, and a statement of estimated cost of reproduction and present value. The division is made by roads, by divisions of roads, and by counties. This was done after the completion of all other work, and the disbanding of the organization, a small force being retained by the State to compile and put in permanent form all the papers of the appraisal. This work was done under the direction of Messrs. James Walker and O. C. Le Suer in consultation with Professor Cooley. The final compilations were typewritten on large sheets and bound, and constitute the final record of the physical valuation. After the completion of the 1900 appraisal, all papers connected with the work of the computing office were arranged in proper order and bound. Special Problems of the Mechanical Department. The Civil Engineering section dealt wholly with fixed property located entirely within the State; and the work offered no special difficulties in the way of assignment of values. It is true that, when the question of terminal values was under discussion, the Wisconsin and Michigan Railroad offered a very pretty example, in that the revenue-producing half of its mileage lay in Michigan, while its shops, yards, docks, and car ferries, comprising the great bulk of its physical property, were in Wisconsin. This instance merely emphasized the fact that no State valuation of an interstate property can settle finally and definitely all the questions that arise. _Assignment of Value to States._—The Mechanical Department was compelled to handle the valuation of moving property, and to assign values as between the States on such a basis as would be fair to all parties. The Courts have been inclined to view the distribution of values between territorial units on the track-mileage basis as being a fair one. The study of the problem in Michigan indicates that while this method, perhaps, is just in most cases, it will not hold in all. Assignment was made upon several bases, as follows: (_a_) Main-line mileage; (_b_) Total track-mileage;