OUSEIIVATIONS WITH THE ZENITH TELESCOPE. 



305 



An example follows for illustrating the process and for showing something of the 

 uniformity of the tube. 



One division of the screw corresponds to one second of arc in the inclination of 

 the bar. 



Thermometer 







Bubble 





Bubble 





Thermometer 







Micrometer 







Mean 







Mean 





o 

 44.S 



N 



a 



N 



S 



44.9 





1 



48 



4.5 



25.2 



14.85 



3.7 



24 4 



14.05 







2 



40 



6.0 



26.7 



10.35 



5.0 



26.3 



15.95 







3 



44 



7.4 



28.1 



17.75 



7.5 



28.2 



17.85 







4 



42 



9.5 



30.3 



19.90 



9.4 



30.2 



19.80 







5 



40 



11.4 



32.2 



21.80 



10.8 



31.5 



21.15 







6 



38 



12.9 



33.7 



23.30 



12.4 



33.1 



22.75 







7 



36 



14.5 



35.2 



24.85 



14.4 



35.1 



24.75 







8 



34 



15.7 



30.4 



26.05 



15.5 



30.3 



25.90 







!) 



32 



17.9 



38.6 



28.25 



10.9 



37.0 



27.25 







10 



30 



19.2 



40.0 



29.00 



18.4 



39.2 



28.80 







11 



28 



20.8 



41.5 



31.15 



20.1 



40.9 



30.50 







12 



26 



22.4 



43.1 



32.75 



21.0 



42.0 



32.25 







18 



24 



24.0 



44.7 



31.35 



23.1 



43.9 



33.50 







14 



22 



24.9 



45.0 



35.25 



24 6 



45.3 



34.95 







15 



20 



26.7 



47.4 



37.05 



20.2 



47.0 



36.60 







16 



18 



28.0 



48.7 



38.35 



27.5 



48.2 



37.85 





9—1 



13.40 



13.20 



10—2 



13.25 



12.85 



11—3 



13.40 



12.05 



12—4 



12.85 



12.45 



13—5 



12.55 



12.35 



14—6 



11.05 



12.20 



15—7 



12.20 



11.85 



16—8 



12.30 



11.95 



16" = 



12.74 



12.44 



vision — 



1".26 



1».29 



The large value given in December was a source of perplexity. No satisfactory 

 explanation for it could be found. The six individual values were as follows : 



1».48 1".47 1".3G 1".47 1".30 1".42 



The value employed in reduction of the Latitude observations was 1".245. 

 This level was examined about one year after the termination of this series, when it 

 was found to have deteriorated to such an extent as to be practically worthless. 



The Micrometer. 



The value of one revolution of the micrometer screw was derived from thirty-seven 



elongations of 51 Cephei, 43 Cephei and S Urate Minoris. The details are given in the 



following table. a, Ursse Minoris was also observed at a number of elongations, but the 



results did not harmonize well, either among themselves or with those derived from the 



* 



