estimates of dose rates at all times, so that the intensities for each area at H + 1 hour also are listed in Table 3.6. 3.4.9 Plotting Fallout Contours of Total Dose. Additional considerations enter into the construction of a contour map relating to total dosage. Time of arrival enters ina different manner. Exposure period covers only the period after the time of arrival to the arbitrary time of H + 50 hours. This exposure period numerically is the difference between 50 hours and the arrival time listed in Column 10 of Table 3.5. Now, for calculation of total exposure doseit is necessary to sum the intensities for all hours between fallout arrival and 50 hours. For conveniencein this task, Figure 3.7 has been drafted so as to indicate accumulated dose when the dose rate at 1 hour is 1 roentgen per hour. This figure together with Columns 9 and 10 of Table 3.5 provides what is needed for computing total dosages along the dry-land track. These dosage numbers were distributed along the track and connected as contours shown in Figure 3.12. tours. Table 3.7 summarizes the total dose accumulated inside the con- 52