DETERMINATION OF DEFLECTION OF LIGHT BY THE SUN'S GRAVITATIONAL FIELD. 307 



When these are applied to the value's of the constants found from the normal equations, 

 we find the following values of the scale of the several photographs and their orientation 

 relative to the scale plate : 



The agreement in the scale values obtained from x and y is satisfactory. There 

 appears to be a small difference in the orientations as derived from the two directions 

 in the comparison plates. This is, however, of small importance in the determination 

 of a. There is a difference of scale value from July 15-18 shown in both co-ordinates. 

 For the purpose of exhibiting the gravitational displacements, residuals have been 

 computed using adopted values for the scale and orientation given above, along with 

 the calculated corrections for differential refraction and aberration. This has the 

 advantage of reducing the number of constants employed in the reduction of the plates, 

 and lessens the possibility of masking any discordances, though greater irregularities 

 necessarily appear when four arbitrary constants instead of six are used in the reduction 



VOL. ccxx. A. 2 IT 



