348 



Introduction to the Seventh Section 



The number of observations of « Herculis, 1 a. and 2 a. Libra: 

 is very small, and on that account I have requested Dr. Arge- 

 lander to observe repeatedly those stars; the results were: 



« Herculis 

 1 « Librae 

 2« ' 



40° 6' 

 69 56 

 69 58 



15' 



3 



46 



If these new observations are joined to the former ones, 

 the numbers of the table are changed into the following : 



20"-01 



6 -59 



48 -48 



17 

 6 

 5 



a Herculis 40° 6' 15"-64 13 

 1 « Librae 69 56 2 -46 7 

 2a 69 58 47 '63 10 



For these calculations the errors of division of the instru- 

 ment have been taken from the table calculated from the for- 

 mula for this error, published in the 1st section of this work, 

 viz. — 2"-446 + 0"-654 sin 2z— 6"'843 cos 2z. 



The more perfect expression for the errors of division is, 

 however, 



-2"-724 + 0''-654 sin 2z-6"-843 cos 2s-0"-25S sin 4s + 

 0"-278 cos 4z 

 and the analogous one found by a new examination after four 

 years use of the instrument, 



-3"-000 + 0"-893 sin 2z-6"'741 cos 2z-0"'172 sin 4z + 



0"-452 cos 4s. Both 





