XIV 



Introduction to the Makerstoun Observations, 1843. 



Table 1. — Values of one of the Long Scale Divisions. 



Observer B. 



Observer W. 



Scale 

 Division. 



Mean of 



three 

 Verniers. 



Scale 

 Division. 



Mean of 



three 

 Verniers. 



Value of 



one 

 Division. 



Scale 

 Division. 



Mean of 



three 

 Verniers. 



Scale 

 Division. 



Mean of 



three 

 Verniers. 



Value of 



one 

 Division. 



160 

 170 

 180 



55 18 46-25 

 55 12 4-17 

 55 5 20-83 



260 

 270 

 280 



o / „ 



54 11 34-17 

 54 4 50-21 

 53 58 2-50 



0-67201 

 67233 

 67305 



180 

 190 

 200 



O / // 



54 59 9-17 

 54 52 22-50 

 54 45 38-33 



280 

 290 

 300 



O / // 



53 51 51-25 

 53 45 7-50 

 53 38 25-00 



0-67300 

 67250 

 67222 



1st series, observer B ; one long scale division = 0'-67247 



2d series, observer W ; = 0'-67257 



The adopted mean value of one division of the long scale of 500 divisions = 0'*6725.* 



Aug. 5. 1843. A short series of observations was made to determine the value 

 of one division of the short scale of 300 divisions. 



Three verniers read ; measures of 50 divisions ; one division of the short scale 



r 0'-7504 1 , r B. 



= (0'-7502J ' ^^^^^^^^ [w. 



Nov. 29. 1843. Two series of observations were made with one vernier. The 

 readings in the following Table are the means of the readings by Mr Welsh and 

 myself. 



Table 2. — Values of one of the Short Scale Divisions. 





First Series. 



Ih. 







Second Series. 



Sh. 





Scale 

 Division. 



Vernier B. 



Scale 

 Division. 



Vernier B. 



Value of 



one 

 Division. 



Scale 

 Division. 



Vernier B. 



Scale 

 Division. 



Vernier B. 



Value of 



one 

 Division. 





o / // 





° / // 



' 





o / // 





O / /, 



/ 



40 



55 26 56-5 



90 



54 49 27-5 



0-74967 



130 



54 11 28-0 



180 



53 34 2-5 



0-74850 



50 



55 19 26-0 



100 



54 41 57-5 



74950 



140 



54 3 58-5 



190 



53 26 31-0 



74902 



60 



55 11 56-0 



110 



54 34 27-5 



74950 



150 



53 56 30-0 



200 



53 19 2-5 



74902 



70 



55 4 3-0 



120 



54 26 52-0 



75267 



160 



53 48 55-0 



210 



53 11 35-0 



74667 



80 



54 56 55-5 



130 



54 19 23-5 



75050 



170 



53 41 32-5 



220 



53 4 3-5 



74967 



1st series ; one division of the short scale of 300 divisions = 0'-7504 



2d series; = 0'-7486 



The adopted value of one division of the short scale = 0'-7500. 



* The differences in the partial results, it is believed, are not due to errors of graduation of the 

 scale, as different comparisons give different results. If greater accuracy could be gained in the read- 

 ings of the horizontal circle, it is obvious that the mean of the angle subtended by one or two hundred 

 scale divisions ought not to be taken as the value of the angle subtended by one scale division. 



