HALL, ABERRATION CONSTANT. 



49 



The errors of the division for every 

 lows : — 



fifth degree are therefore as 



fol- 



0' 



5 



10 



15 



20 



25 

 30 

 35 

 40 

 45 



50 

 55 

 60 

 65 

 70 



0.00" 



+1.51 

 —0.31 

 + 1.00 

 +0.67 



+ 1.76 

 + 1.30 

 +3.00 

 + 1.86 

 +3.36 



+3.20 

 +4.31 

 +3.73 

 +5.11 



+4.47 



75° 



80 

 85 

 90 

 95 



100 

 105 

 110 

 115 

 120 



125 

 130 

 135 

 140 

 145 



+5.91" 

 5.10 

 6.44 

 5.46 

 6.69 



5.26 

 6.78 

 5.72 

 6.58 

 6.45 



6.81 

 7.18 

 7.15 

 7.18 

 6.82 



225' 

 230 

 235 

 240 

 245 



250 

 255 

 260 



265 

 270 



275 

 280 

 285 

 290 

 295 



+7.65' 

 5.81 

 6.91 

 4.46 

 4.93 



3.39 

 4.23 

 3Tti9 



2.19 

 2.20 



1.18 

 1.93 

 1.62 

 1.36 

 1.67 



300' 

 305 

 310 

 315 

 320 



325 



330 

 335 

 340 

 345 



350 

 355 



+0.58" 

 +0.83 

 -0 04 

 -0.48 

 -0.43 



—0.42 

 -0 05 

 -0 78 

 -0.49 

 —1.31 



40.13 

 —1.66 



The errors thus found are not merely thos'e of the divisions, bnt include 

 also the errors owing to the eccentricity of the circle and to the deviation 

 of the pivots from a cylindricnl form. The eccentricity produces terms of 

 the form 



a + b cos X + c sin x ; 



and from the 72 errors given above, T find the error of the eccentricity, 



+ 4.''044 — 3."835 cos x + l."o61 sin x, 



or +4.''044— 4.141cos(x + 22°9'). 



7 



