402 



Special Reports 



No. 1911 by Toepfer and No. 89 by Toepfer of the Dominion Observatory and Agincourt 

 respectively, particularly so as the examination in 1921 of No. 20 showed that its lifting 

 wyes had changed in adjustment, doubtless owing to long field service. It is, however, 

 interesting to note that the weighted mean value of (I. M. S. at Ottawa D. O. No. 20) 

 from 27 sets of 4 needles each in 1916 and 1917 and of (I. M.S. at Agincourt D.O. 

 No. 20) from 12 sets of 4 needles each in 1919 and 1920 as determined by Mr. French, 

 using (I. M. S D. O. No. 1911) = -0'.25 (see p. 419) and (I. M. S Agincourt No. 89) 

 = -0M5 (see p. 400), is -O'.l. The mean value of (I. M.S. at Washington D. O. 

 No. 20) determined in 1915, +0'.l, and again in 1921, -0'.3, is -O'.l. 



From the indirect comparisons of 1915 to 1921 as in Table IF, we have: 



(J) I. M. S. Agincourt (Toronto declinometer) = l'.3. 



(k) I. M. S.-Agincourt (Elliott magnetometer No. 98)= +0.00038/7 (weight 3). 



Table IF. Results of Indirect Comparisons at Agincourt Observatory through Dominion Observatory Magnetometer 



No. 20, 1915-1921. 



'Values for 1916 to 1920 interpolated linearly between observed values for 1915 and 1921. 



2 After minor repairs. 



Referred to 1915 value of moment of inertia of long magnet and stirrup. 



SUMMARY. 



The above results confirm the published results as given in Volume II" of previous 

 comparisons in declination and horizontal intensity, particularly so as the previous 

 comparisons were without exchange of stations and, therefore, are not corrected for 

 small station-differences. In view of the uncertainties involved in the transfer of dip- 

 circle standards to that of the inductor because of the considerably greater precision of 

 the inductor and lack of knowledge of station-differences at Agincourt between stations 

 used in the earlier work, the results from the comparison at Washington are accepted 

 for inclination. 



Thus we adopt from the above : 



( I ) I . M. S. - Agincourt (Toronto declinometer) = - I '.3 ( I 906- 1915). 

 (la) I. M. S.-Agincourt (Elliott magnetometer No. 98) = +0.00039/7 (1911-1915). 

 (It) I.M. S.-Agincourt (Toepfer inductor No. 89)=-0M5 at pier E (1912-1921). 

 (lc) I. M.S. Agincourt (Toronto declinometer at pier A 0'.9) =0'.0 at pier (1916- 



1921). 

 (I a") I.M. S.-Agincourt (Elliott magnetometer No. 98 at pier +0.00039/7 = 0.00000// 



(1916-1921). 

 ( I c) I . M. S. - Meteorological Service (C. I . W. magnetometer No. I 5) = - 0'.9 ( 1 9 1 5). 

 (I/) I . M. S. - Meteorological Service (C. I . W. magnetometer No. 1 5) = +0.00007/Y (1915). 



See Res. Dep. Terr. Mag., Vol. II, pp. 213-216. 



