Reduction Formula and Instrumental Constants 



253 



being 7.5 cm. long, with inside diameter of 0.75 cm. and outside diameter of 1.00 cm., and 

 the short magnets being 3.5 cm. long, with inside diameter of 0.61 cm. and outside diameter 

 of 0.82 cm. Universal magnetometers 14, 19, and 21, and magnetometer-inductor 25 

 were designed and constructed by the Department of Terrestrial Magnetism; the magnets 

 are hollow cyhnders, the long magnets being 5.6 cm. long, with inside diameter of 0.60 cm. 

 and outside diameter of 0.79 cm., and the short magnets being 2.6 cm. long, with inside 

 diameter of 0.45 cm. and outside diameter of 0.65 cm. Phosphor-bronze-ribbon suspen- 

 sions were used for all these instruments. 



Table 62. — Details and Constants of Magnetometers Used, 1909-1914. 



(The c. G. 8. eyatem of units is used throughout the table; the value of q is given for 1°C.| 



'Magnetometer 3 is the standard magnetometer of the Department of Terrestrial Magnetism. 

 'This value of P is the value of P', assuming that (1 + P'r' ') = (1 + Pr'' + Qr'*). 



The dip-circles and universal magnetometers used to determine inclination at shore 

 stations were of the patterns which are fully described and illustrated in Volumes I (pp. 

 7-10) and II (pp. 7-9), viz: (o) the regular Kew land-pattern as made by Dover; (6) the 

 sea dip-circle pattern (see p. 195) as made by Dover, and which was used for Cruise I; 

 and the dip-circle attachment of the universal-magnetometer pattern, 4 (6), designed and 

 consti-ucted by the Department of Terrestrial Magnetism. To determine the magnetic 

 decUnation at shore stations, a compass attachment, fully described and illustrated in 

 Volume I (p. 9), was provided for each land and sea dip-cLrcle. (See also this volume, pp. 

 21-23). 



The earth inductors used to determine the inclination at shore stations were of the 

 patterns which are fully described and illustrated in Volumes I (pp. 10-11) and II (pp. 

 9-15), and in this volume (pp. 196-200), viz: (a) the Wild-Eschenhagen pattern as made by 

 Schulze and by Toepfer & Sohn; (6) the marine pattern, and the earth-inductor attach- 

 ment of the magnetometer-inductor pattern, 4 (c) ; the last two types were designed and 

 constructed by the Department of Terrestrial Magnetism. Earth-inductor 48, constructed 

 by Schulze, and fully described and illustrated in Volume I (pp. 10-11), was the standard 

 inclination instrument of the Department of Terrestrial Magnetism during 1909-1916. 



