194 VALUATION, DEPRECIATION AND THE RATE-BASE 
only or that failed for any reason to fulfill their intended 
purpose. 
The cost records are not always dependable and they may 
have to be either entirely disregarded or largely supplemented 
by cost estimates. Recourse may be had in such cases to the 
cost of reproduction as a means of approximating the amount 
that may reasonably be assumed to be properly invested in the 
property. In making the estimate of the cost of reproduction 
it is not advisable to use the prices of materials and labor 
momentarily prevailing but rather the average for a consider- 
able time period, preferably about 5 years. 
Tabulation of Field Results. — The results of the field exami- 
nation, including a classified enumeration of the physical items 
that go to make up the property, should be tabulated in con- 
venient form on sheets which will show in appropriate columns 
information about as follows: 
1. The year of installation. 
2. The age. 
>», The probable life new. 
+» The expectancy or estimated remaining years of service. 
The cost to reconstruct, itemized. 
. The sub-totals of (3). 
7. The contractor’s profit. 
8. The totals of (6) and (7). 
9. The allowance for overhead expenses. 
10. The total investment, estimated as the sum of (8) and (9). 
11. The residual or scrap value. 
12. The present value, in per cent, computed from (3) and 
(4) (sometimes called condition per cent). 
13. The remaining or present value in dollars (computed 
from (10), (11), and (12)). 
14. The accrued depreciation (10) — (13). 
15. The current rate of depreciation (computed from (3), 
(4), (10) and (11). 
It will be noted that according to this tabulation the cost to 
reconstruct and the residual or scrap value are considered when