Compare the observed P-phase travel times with travel times computed assuming a constant velocity throughout the Earth.
(Travel times are from this site:  http://neic.usgs.gov/neis/travel_times/s-p_table.html )
Radius of Earth (km) 6360.00
Radians per degree 0.0175
Arc Length Cord Length Constant Velocity
Delta Delta P Travel Time P Travel Time R*Delta (km) 2*R*sin(Delta/2) Earth Travel Time
degrees radians minutes seconds seconds kilometers kilometers seconds
0.00 0.00 0.00 5.40 5.40 0.00 0.00 0.00
0.50 0.01 0.00 10.60 10.60 55.50 55.50 8.85
1.00 0.02 0.00 17.70 17.70 111.00 111.00 17.70
1.50 0.03 0.00 24.60 24.60 166.50 166.50 26.55
2.00 0.03 0.00 31.40 31.40 222.01 221.99 35.40
2.50 0.04 0.00 38.30 38.30 277.51 277.49 44.25
3.00 0.05 0.00 45.20 45.20 333.01 332.97 53.09
3.50 0.06 0.00 52.10 52.10 388.51 388.45 61.94
4.00 0.07 0.00 58.90 58.90 444.01 443.92 70.79
4.50 0.08 1.00 5.80 65.80 499.51 499.38 79.63
5.00 0.09 1.00 12.70 72.70 555.01 554.84 88.47
5.50 0.10 1.00 19.60 79.60 610.52 610.28 97.31
6.00 0.10 1.00 26.40 86.40 666.02 665.71 106.15
6.50 0.11 1.00 33.30 93.30 721.52 721.13 114.99
7.00 0.12 1.00 40.20 100.20 777.02 776.54 123.82
7.50 0.13 1.00 47.00 107.00 832.52 831.93 132.66
8.00 0.14 1.00 53.90 113.90 888.02 887.30 141.49
8.50 0.15 2.00 0.70 120.70 943.52 942.66 150.31
9.00 0.16 2.00 7.60 127.60 999.03 998.00 159.14
9.50 0.17 2.00 14.40 134.40 1054.53 1053.32 167.96
10.00 0.17 2.00 21.30 141.30 1110.03 1108.62 176.78
11.00 0.19 2.00 35.00 155.00 1221.03 1219.16 194.40
12.00 0.21 2.00 48.70 168.70 1332.03 1329.60 212.01
13.00 0.23 3.00 2.30 182.30 1443.04 1439.94 229.61
14.00 0.24 3.00 16.00 196.00 1554.04 1550.18 247.18
15.00 0.26 3.00 29.50 209.50 1665.04 1660.29 264.74
16.00 0.28 3.00 42.50 222.50 1776.05 1770.28 282.28
17.00 0.30 3.00 55.20 235.20 1887.05 1880.13 299.80
18.00 0.31 4.00 7.50 247.50 1998.05 1989.84 317.29
19.00 0.33 4.00 18.80 258.80 2109.05 2099.40 334.76
20.00 0.35 4.00 29.70 269.70 2220.06 2208.80 352.21
21.00 0.37 4.00 40.60 280.60 2331.06 2318.03 369.62
22.00 0.38 4.00 51.30 291.30 2442.06 2427.09 387.01
23.00 0.40 5.00 1.90 301.90 2553.07 2535.96 404.37
24.00 0.42 5.00 11.60 311.60 2664.07 2644.63 421.70
25.00 0.44 5.00 20.70 320.70 2775.07 2753.11 439.00
26.00 0.45 5.00 29.80 329.80 2886.07 2861.38 456.26
27.00 0.47 5.00 38.80 338.80 2997.08 2969.42 473.49
28.00 0.49 5.00 47.70 347.70 3108.08 3077.24 490.68
29.00 0.51 5.00 56.60 356.60 3219.08 3184.83 507.84
30.00 0.52 6.00 5.50 365.50 3330.09 3292.18 524.96
31.00 0.54 6.00 14.30 374.30 3441.09 3399.27 542.03
32.00 0.56 6.00 23.10 383.10 3552.09 3506.10 559.07
33.00 0.58 6.00 31.90 391.90 3663.09 3612.67 576.06
34.00 0.59 6.00 40.50 400.50 3774.10 3718.97 593.01
35.00 0.61 6.00 49.20 409.20 3885.10 3824.97 609.91
36.00 0.63 6.00 57.80 417.80 3996.10 3930.69 626.77
37.00 0.65 7.00 6.30 426.30 4107.11 4036.11 643.58
38.00 0.66 7.00 14.70 434.70 4218.11 4141.22 660.34
39.00 0.68 7.00 23.10 443.10 4329.11 4246.02 677.05
40.00 0.70 7.00 31.40 451.40 4440.11 4350.49 693.71
41.00 0.72 7.00 39.70 459.70 4551.12 4454.63 710.32
42.00 0.73 7.00 47.90 467.90 4662.12 4558.44 726.87
43.00 0.75 7.00 56.00 476.00 4773.12 4661.89 743.36
44.00 0.77 8.00 4.10 484.10 4884.13 4764.99 759.80
45.00 0.79 8.00 12.10 492.10 4995.13 4867.73 776.19
46.00 0.80 8.00 20.00 500.00 5106.13 4970.10 792.51
47.00 0.82 8.00 27.80 507.80 5217.13 5072.08 808.77
48.00 0.84 8.00 35.60 515.60 5328.14 5173.69 824.97
49.00 0.86 8.00 43.30 523.30 5439.14 5274.89 841.11
50.00 0.87 8.00 50.90 530.90 5550.14 5375.70 857.18
51.00 0.89 8.00 58.50 538.50 5661.15 5476.10 873.19
52.00 0.91 9.00 6.00 546.00 5772.15 5576.08 889.14
53.00 0.93 9.00 13.40 553.40 5883.15 5675.63 905.01
54.00 0.94 9.00 20.70 560.70 5994.15 5774.75 920.82
55.00 0.96 9.00 28.00 568.00 6105.16 5873.44 936.55
56.00 0.98 9.00 35.20 575.20 6216.16 5971.67 952.22
57.00 0.99 9.00 42.30 582.30 6327.16 6069.45 967.81
58.00 1.01 9.00 49.40 589.40 6438.17 6166.77 983.33
59.00 1.03 9.00 56.30 596.30 6549.17 6263.62 998.77
60.00 1.05 10.00 3.20 603.20 6660.17 6360.00 1014.14
61.00 1.06 10.00 10.10 610.10 6771.17 6455.88 1029.43
62.00 1.08 10.00 16.80 616.80 6882.18 6551.28 1044.64
63.00 1.10 10.00 23.50 623.50 6993.18 6646.18 1059.77
64.00 1.12 10.00 30.10 630.10 7104.18 6740.57 1074.82
65.00 1.13 10.00 36.70 636.70 7215.19 6834.45 1089.79
66.00 1.15 10.00 43.20 643.20 7326.19 6927.80 1104.68
67.00 1.17 10.00 49.50 649.50 7437.19 7020.63 1119.48
68.00 1.19 10.00 55.90 655.90 7548.19 7112.93 1134.19
69.00 1.20 11.00 2.10 662.10 7659.20 7204.68 1148.83
70.00 1.22 11.00 8.30 668.30 7770.20 7295.89 1163.37
71.00 1.24 11.00 14.40 674.40 7881.20 7386.54 1177.82
72.00 1.26 11.00 20.40 680.40 7992.20 7476.62 1192.19
73.00 1.27 11.00 26.40 686.40 8103.21 7566.14 1206.46
74.00 1.29 11.00 32.30 692.30 8214.21 7655.08 1220.64
75.00 1.31 11.00 38.10 698.10 8325.21 7743.44 1234.73
76.00 1.33 11.00 43.80 703.80 8436.22 7831.21 1248.73
77.00 1.34 11.00 49.50 709.50 8547.22 7918.38 1262.63
78.00 1.36 11.00 55.10 715.10 8658.22 8004.95 1276.43
79.00 1.38 12.00 0.60 720.60 8769.22 8090.91 1290.14
80.00 1.40 12.00 6.00 726.00 8880.23 8176.25 1303.75
81.00 1.41 12.00 11.40 731.40 8991.23 8260.97 1317.26
82.00 1.43 12.00 16.70 736.70 9102.23 8345.07 1330.67
83.00 1.45 12.00 21.90 741.90 9213.24 8428.52 1343.97
84.00 1.47 12.00 27.00 747.00 9324.24 8511.34 1357.18
85.00 1.48 12.00 32.00 752.00 9435.24 8593.50 1370.28
86.00 1.50 12.00 37.00 757.00 9546.24 8675.01 1383.28
87.00 1.52 12.00 41.90 761.90 9657.25 8755.86 1396.17
88.00 1.54 12.00 46.70 766.70 9768.25 8836.05 1408.96
89.00 1.55 12.00 51.40 771.40 9879.25 8915.56 1421.63
90.00 1.57 12.00 56.10 776.10 9990.26 8994.39 1434.20
91.00 1.59 13.00 0.70 780.70 10101.26 9072.54 1446.67
92.00 1.61 13.00 5.40 785.40 10212.26 9150.00 1459.02
93.00 1.62 13.00 10.00 790.00 10323.26 9226.76 1471.26
94.00 1.64 13.00 14.50 794.50 10434.27 9302.81 1483.38
95.00 1.66 13.00 19.10 799.10 10545.27 9378.16 1495.40
96.00 1.68 13.00 23.60 803.60 10656.27 9452.80 1507.30
97.00 1.69 13.00 28.10 808.10 10767.28 9526.71 1519.09
98.00 1.71 13.00 32.60 812.60 10878.28 9599.90 1530.76
99.00 1.73 13.00 37.00 817.00 10989.28 9672.36 1542.31
100.00 1.75 13.00 41.50 821.50 11100.28 9744.08 1553.75
101.00 1.76 13.00 45.90 825.90 11211.29 9815.06 1565.06
102.00 1.78 13.00 50.40 830.40 11322.29 9885.29 1576.26
103.00 1.80 13.00 54.80 834.80 11433.29 9954.77 1587.34
104.00 1.82 13.00 59.20 839.20 11544.30 10023.49 1598.30
105.00 1.83 14.00 3.70 843.70 11655.30 10091.45 1609.14