314 



PRITCHARD S WEDGE PHOTOMETER. 



Setting on Slit (before mounting prism) 0° 0' 0". 



u 



D 2 * (after 



.. 



« 



) 315° 47' 30". 



Current of Battery = 0.040 Ampere. 



Header (alternately) at Circle and Wedge, J. P. 



« 



Object 



at Galvanometer, F. W. V. 



measurement of transmission of Pritchard wedge for different parts of the spectrum 



Time 11.30 a.m. to 2.05 p.m. 



TABLE III. 



>0*.4 



(Dev. 46 



Me;in of S ries 1 



■*<K5 



(Dev. 44 



Mean of Series 2 



0".6 



(Dev. 44 



Mean of Series 3 



^0^.7 



(Dev. 43° 37') 



Wedge 

 Wedge. I at 0.3 in . 



40.7 

 3577 



38.2 



174.0 



174.0 



174.0 



347.0 



338.0 



Moan of Series 4 



343.0 



520.0 



533.0 



527.0 



>1^.0 



(Dev. 42 



Mean of Series 5 



822.0 



835.0 



829.0 



47.5 



50.5 



49.0 



99.0 

 100.0 



99.5 



225.0 

 261.0 



Wedge 

 at 1.8 in 



243.0 



504.0 

 454.0 



479.0 



"Wedge 

 at 3.3 in. 



12.9 

 14.4 



13.7 



61.4 



68.0 



64.7 



Wedge 

 at 4.8 in 



17.3 

 16.0 



16.7 



Wedge 

 at 6.3 in 



267.0 

 213.0 



137.0 

 122.0 



65.0 

 62.0 



240.0 



129.0 



63.5 



34.2 

 35.0 



34.6 



PRISMATIC OBSERVATIONS OF WEDGE TRANSMISSION OF AUGUST 9, 1886. 



Extract from Original Record. 



Temperature of Apparatus = 25°.3 C. at 11 a.m. 



>/ 



>/ 



P 



of the we dire.) 



2 mm. (Height of slit is to-day reduced to 11 mm., or slightly less than that 



Galvanometer, No. 3 (damping magnet at 70 cm.). 



>/ 



14 seconds. 



* An optical setting on the sodium line D a is always made as a check on the accuracy of adjustment of the 

 prismatic apparatus. 



