Different engineers have included in the appraisal other items which are of a somewhat different nature, and some of which are open to argument; among these are "interest during construction." This item is clearly an allowable one, but serious differences of opinion develop as to a proper amount to allow in making an appraisal. The corporate history of the Ann Arbor Railroad, in Michigan, shows that it was built in sections of from 25 to 30 miles, and that each section was put into operation as soon as built, so that, while the actual period of construction of the complete property extended over 15 years, no section was under construction much more than one year. This is typical of much of the railroad building of the past, and on such a property the interest charge would be comparatively small. A proper charge in such a case would clearly not be sufficient in the case of a road several hundred miles in length, through mountains, with tunnels, heavy bridges, and other structures which would extend the actual construction over periods of from 3 to 5 or 6 years, and this is particularly true where the road is a main line or artery, and where local traffic is of minor importance. The computation of the interest charge is complicated by the fact that interest begins to run as the bonds are taken up, and but a small part of the construction money draws interest during the whole period. The practice in the State appraisals has been to fix a uniform percentage for all properties. This has had in its favor the argument that it was conservative valuation where taxation is the ultimate end, as the amount was less than one year's interest in every case. It would appear to be more correct to use the corporate history of each company, determine the actual construction periods, and use a rate based on the actual time in each case. This can be fixed with a fair degree of accuracy, and a reasonable percentage determined, to equalize the varying periods of time on which the interest runs on different parts of construction. Discount.—Discount on bonds is claimed by certain railroad men as a proper item for consideration. As has been argued elsewhere, this is not a proper charge against capital. It is an adjustment of the interest rate to the market, or an advance payment of interest; and, in the writer's opinion, should under no consideration be allowed.