172 



ASTRONOMY. 



Computations fiom observations on Polaris, tvestern elongation, for the determination of the value 

 of one division of the micrometer attached to zenith telescope, by Wurdemann, for the U. S. 

 Boundary Commission. 3Iarch 23, 1855. 



No 



Micrometer Times of ob- 



I 



readings. 



1 



* 



1 



300 



9 



950 



3 



150 



4 



100 



5 



50 



6 



GO 



7 



100 



8 



150 



9 



250 



10 



350 



11 



450 



12 



500 



13 



550 



14 



600 



servai'n by 

 chron'r. 



A. m- 5. 

 6 15 48.0 



17 12.0 



20 5.8 



21 31.5 



22 55.5 

 24 19.2 

 27 9.2 

 98 34.0 

 31 20. 

 34 11.0 

 36 55.0 



38 19.0 



39 40.0 

 41 4.2 



Time from 

 elongation. 



tn. 



20.91 



19.52 

 16.62 



15.19 

 13.79 

 12.40 

 9.56 

 6.10 

 5.38 

 2.53 

 0.18 

 1.59 

 2.94 

 4.34 



Correct'n for Reduced time. 

 H. 



1.8 

 1.4 

 0.9 

 0.7 



0.5 

 0.3 



0.1 



0.1 

 0.0 

 0.0 

 0.0 

 0.0 

 0.0 

 0.0 



A. m. 5* 



6 15 49.8 



17 13.4 



20 6.7 



21 32.2 



22 56.0 

 24 19.5 



27 9.3 



28 34.1 



■ 



31 20.0 

 34 11.0 

 36 55.0 



38 19.0 



39 40.0 

 41 4.2 



Nos 



1 to 6 

 5 



3 



2 

 2 to 6 



6 to 14 



13 

 12 

 11 

 10 

 9 

 8 



7 to 14 



Difference 

 of time. 



tn. s. 



8 29.7 



7 6.2 



5 42.4 



4 16.9 



1 23.6 



7 6.1 



16 44.7 



15 20.5 



13 59.5 



12 35.5 



9 51.5 

 7 0.5 

 4 14.6 



13 54.9 



Diflerence of 

 time in arc. 



9 7 25.5 

 1 46 33.0 

 1 25 36.0 



1 4 13.5 

 20 54.0 



1 46 31.5 

 4 11 10,5 

 3 50 7.5 

 3 29 52.5 

 3 8 52.5 



2 27 52.5 

 1 45 7.5 

 1 3 39.0 



3 28 43.5 



Reduction 



to the 



equator. 



t rr 



3 15.0 



2 43.1 

 2 11.0 



1 38.3 

 32.0 



2 43.0 

 6 25.1 

 5 51.9 

 5 21.0 



4 49.0 



3 46.2 

 2 41.1 



1 37.4 

 5 19.3 



DiiT. of mi- 

 crometer 



readings. 



300 

 250 

 150 

 100 

 50 

 250 

 600 

 550 

 500 

 450 

 350 

 250 

 150 

 500 



Resulting 



values of one 



division. 



0.65000 

 . 65200 

 . 65500 

 . 65500 

 0.64000 

 0.65280 

 0.64183 

 0.63982 

 0.64200 

 . 642*2 

 0.64639 

 0.64440 

 0.64933 

 0.63660 



Mean 



9 04939 



14 



0^'.64C38by 1st seiics. 



Sum = 9.04939 



ReniarJcs. 



Chronometer slow 



Time, by chronometer, of western elongation of Polaris 



Declination of star 



28m. 415.490 

 6/i. 36m. 43S.350 

 88=' 32' 17/\4 



Observer, Lieut. N. Michler, Top. Engineers, U. S. A. Computer, Hugh Campbell. 



No. 



1 



7 



9 

 10 



11 

 12 

 13 



14 



Commutations for the value of one division of the micrometer ^ &c. — Continued. 



Micrometer Time of ob- Time from 

 readings. servai*nby : elongation. 



mic'ter. 



I 



Oorrect'n for Reduced time. 

 H. 



N03. 



Differe n ce 

 of time. 





Difference of 

 time in arc. 



300 

 250 

 150 

 100 

 50 

 

 100 

 150 

 250 

 350 

 450 

 500 

 550 

 600 



A. m. s. 



6 15 48.0 



17 12.0 



20 5.8 



21 31.5 



22 55 5 



24 19.2 



27 9.2 



28 34.0 

 31 20.0 

 34 11.0 

 36 55.0 



38 19.0 



39 40.0 

 41 4.2 



m. 



20.91 



19.52 



16.62 



15.19 



13.79 



12.40 



9.56 



8.10 



5.38 



2.53 



0.18 



1.59 



2.94 



4,34 



1.8 

 1.4 

 0.9 

 0.7 

 0.5 

 0.3 

 0.1 

 0.1 

 0.0 

 0.0 

 0.0 

 0.0 

 0.0 

 0.0 



A. 37l< Sm 



6 15 49.8 

 17 13.4 



20 6.7 



21 32.2 

 ^ 56.0 

 24 19.5 



27 9.3 



28 34.1 

 31 20.0 

 34 11. 

 36 55.0 



38 19.0 



39 40.0 

 41 4.2 



Mean 



lat series 



2d series 



Mean 



// 



0.64638 

 0.64001 



0.643195 



1 SI m ean 



9d mean 



7 to 13 



12 

 11 

 10 



8 to 14 



13 



12 



11 



14 to 1 



13 to 2 



12 to 3 

 11 to 4 



14 to 2 



13 to 3 



m. ». 



13 54.9 



12 30.7 



11 9.7 

 9 45.7 



12 30.1 

 11 5.9 



9 44.9 



8 20.9 



25 14.4 



22 26.6 



18 12.3 

 15 22.8 



23 50.8 



19 33.3 



3 7 40.5 

 2 47 25.5 



2 26 25.5 



1 45 25.5 



3 7 31.5 



2 46 28.5 

 2 26 13.5 



2 5 13.5 

 6 18 36.0 

 5 36 39.0 



4 33 4.5 



3 50 42.0 



5 57 42.0 



4 53 19.5 



f 



8.96018 



0''.64001 by 2d series 



1 Ht sum . 

 2d sum. 



9.04939 

 8.96018 



Reduction 



to the 



equator. 



r n 

 4 47.1 



4 16.1 



3 44.0 



2 41.4 



4 45.9 



4 14.7 



3 43.7 

 3 11.6 

 9 38.3 



8 34.4 



6 57.5 



5 52.8 



9 6.5 



7 28.4 



Diff. of mi- Value of one 

 crometcr divis'nof the 

 readings, micrometer 



- 



450 

 400 

 350 

 250 

 450 

 400 

 350 

 300 

 900 

 800 

 650 

 550 

 850 

 700 



// 

 0.63800 



0.64025 

 0.64000 

 0.64560 

 0.63533 

 0.63675 

 0.63914 

 0.63866 

 0.64255 

 0.64300 

 0.64230 



. 63600 

 0,64294 

 0.64066 



Sum = 8.96018 



^Q-^^^T ^ 0^'. 643198 = mean of 28 combinations 



28 



n 

 0.643195 



0.643198 



Result by Polaris 



0.643196 



Ubaerverj Lieut. N. Michler, Top. Engineers, U. 9. A. Computer, Hugh Campbell 



