| N | = | 6, | | R | = | 0, | | R' | = | .01, | | T | = | 20.29, | | T' | = | 22.83, | |
| T" | = | | 20.29 + 22.54 + 22.84 + 22.88 + 22.87 + 22.86 | | –––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– | | 6 |
| = | 22.36 |
| C | = | 6 | | ( | 0 | + | | .01 - 0 | | ––––––––––––––––––––– | | 22.85 - 20.29 |
| ( | 22.36 - 20.29 | ) | ) |
|
Pfaundler’s formula while simple is rather long. Mr. E. H. Peabody has devised a simpler formula with which, under proper conditions, the variation from correction as found by Pfaundler’s method is negligible.
It was noted throughout an extended series of calorimeter tests that the maximum temperature was reached by the thermometer slightly over one minute after the time of firing. If this period between the time of firing and the maximum temperature reported was exactly one minute, the radiation through this period would equal the radiation per one-half minute before firing plus the radiation per one-half minute after the maximum temperature is reached; or, the radiation through the one minute interval would be the average of the radiation per minute before firing and the radiation per minute after the maximum. A plotted chart of temperatures would take the form of a curve of three straight lines (B, C', D) in Fig. 25. Under such conditions, using the notation as in formula ([19]) the correction would become,
| C | = | | + | ( | N - 2 | ) | R', | or R | + | (N - 1)R' | (20) |
This formula may be generalized for conditions where the maximum temperature is reached after a period of more than one minute as follows:
Let M = the number of intervals between the time of firing and the maximum temperature. Then the radiation through this period will be an average of the radiation for M intervals before firing and for M intervals after the maximum is recorded, or