Specimen Observations on the Galilee 



55 



Computation of Magnetic Observations, April 14, 1908. 



The foregoing observations on course were computed in the same way as were the swing 

 observations, explained on pages 33 to 46. It was necessary to apply to each course value 

 of an element the proper deviation-correction, derived as explained on pages 91-92. 



In the case of the declination observations given on pages 47-48, each set was com- 

 puted, using Form 22 as shown on page 35. The results of the computations were as follows : 



Table 2— Values of the Magnetic Declination on April I4, 1908, from A. M. Observations. 

 (Latitude, 6° 01' S; longitude, 98° 30' W.) 



Instru- 

 ment 



R3C 

 R3C 

 R3C 

 R3C 



D2 

 D2 

 D2 

 D2 



Set 



Method 



Priam 

 Prism 

 Alidade 

 Alidade 



Prism 

 Prism 

 Alidade 

 Alidade 



Local 



Apparent 



Time 



h m s 



6 12 16 



6 24 55 



6 13 57 



6 23 14 



6 16 34 



6 22 03 



6 18 36 



6 20 34 



Sun by 

 Compass 



N70.79E 

 70.88 

 71.94 

 70.94 



N 71.86 E 

 71.80 

 70.70 

 71.50 



Instrumental 

 Correction 



+ .03 

 + .03 

 + .02 

 + .03 



.00 



.00 



+ .01 



+ .01 



+ .28 

 + .28 



.54 

 .54 



+ .06 

 + .06 



+ .04 

 + .04 



Corr'd 

 Compass 

 Reading 



N 71.10 E 

 71.19 

 72.02 

 71.03 



N71 32E 

 71 26 

 70.75 

 71 55 



T.\BLE Z— Values of the Magnetic Declination on April I4, 1908, from P. M. Observations. 

 (Latitude, 5° 41' S; longitude, 99° 55' W.) 



Instru- 

 ment 



R3C 

 R3C 

 R3C 

 R3C 



D2 

 D2 

 D2 

 D2 



Set 



Method 



Prism 

 Prism 

 Ahdade 

 Alidade 



Prism 

 Prism 

 Alidade 

 Alidade 



Local 



Apparent 



Time 



16 44 



s 



00 

 17 04 01 



16 46 42 



17 01 43 



16 49 25 



16 59 10 



16 51 35 



16 57 06 



Corr'd 

 Compass 

 Reading 



N 87.04 W 

 87.83 

 87.32 

 87.91 



N87.47 W 

 87.92 

 87.53 

 87 97 



Sun's 

 Azimuth 



N 78.08 W 

 78.85 

 78.20 



78.78 



Means 



N 78.30 W 

 78.68 

 78.39 

 78.60 



Obs'd 

 Decl'n 



Devia- 

 tion- 

 Corr'n 



+8.96 

 +8.98 

 +9.12 

 +9.13 



+9.05 



+9.17 

 +9.24 

 +9.14 

 +9.37 



Means +9.23 -.21 



.08 

 .08 

 .08 

 .08 



.08 



.21 

 .21 

 .21 

 .21 



Corr'd 

 Decl'n 



+8.88 

 +8.90 

 +9 04 

 +9.05 



+8.97 



Weighted mean . 



+8.96 

 +9.03 

 +8.93 

 +9.16 



+9.02 



+8.99 



Thus, after instrumental corrections had been applied, the mean of the four sets of 

 a. m. observations with R3C was -f-8?83. The corresponding value for D2 was ■4-8?93. 

 The respective deviation-corrections (see p. 92) were — 0?08 and — 0?21, giving as the 

 final values of the magnetic declination, 8?75 E by the standard compass (R3C) and 8?72 

 E by the sea deflector (D2). The final weighted mean, compass weight 2, deflector weight 

 1, was 8?74 E or 8° 44' E, (latitude, 6° 01' S; longitude, 98° 30' W), as given in the Table 

 of Results (p. 104). The standard compass,R3C, was given weight 2 as compared with 



