the Magnetic Compass in Aeroplanes. 



Vol 



the compass-bowl o£ an aero-compass. Two sets of magnets 

 are used, one, a pair of 8-inch magnets, and the other, 4-inch 

 magnets. The lubber line being set N. and S., the magnets 

 are placed in position one at a time and their level adjusted 

 with the arm horizontal, until the card is in equilibrium in 

 the magnetic meridian. 



For various tilts of the arm 0, the deflexions are observed. 

 The tangents of the deflexions are plotted against 6, thus 

 giving a number proportional to the deflecting couple. The 

 values of 6 and of — 9 are observed, but the deflexions for 

 the latter are so near the former that, after the first obser- 

 vations, only those for one direction of rotation of the arm 

 ( + 0) were observed. 



For values of 6 near 90° the deflexion approaches 90°, and 

 the readings of the deflexion become difficult to make with 

 sufficient precision to give the tangent of the deflexion 

 accurately. 











8-inch magnets. 













^=16 



cm. * 





d=18 cm. 



d=20 cm. 



9. 

 



Compass 

 card. 



Defl. 



tan 

 dell. 



9. 



Card. 



Defl. 



tan 

 dell. 



9. 



Card. 



Defl. 



tan 

 defl. 



180° 















180 















180 









5 



206 



26 



048 



o 



199 



19 



034 



5 









10 



228 



48 



11 



10 



215 



35 



070 



10 



210 



30 



0-58 



20 



244 



64 



24 



20 



236 



56 



15 



20 



230 



50 



1-2 



30 



252 



72 



3-1 



30 



245 



65 



21 



30 



240 



60 



17 



40 



254 



74 



35 



40 



250 



70 



2-7 



40 



244 



64 



21 



50 



258 



78 



47 



50 



252 



72 



31 



50 



248 



68 



2-5 



60 



260 



80 



5-7 



60 



254 



74 



35 



60 



249 



69 



2-6 



70 



260 



80 



57 



70 



254 



74 



35 



70 



250 



70 



2-7 



80 



2(50 



80 



5-7 



80 



255 



75 



37 



80 



250 



70 



2-7 



90 



260 



80 



57 



90 



255 



75 



3-7 



90 



250 



70 



2-7 











4-i 



nch u 



lagne 



its. 











10 



211 



31 



06 



10 



205 



25 



041 



10 



200 



20 



0-36 



20 



233 



53 



1-3 



20 



225 



45 



1-0 



20 



213 



33 



0-65 



ao 



241 



61 



1-8 



30 



234 



54 



T4 



30 



224 



44 



0-97 



40 



246 



66 



22 



40 



240 



60 



17 



40 



230 



50 



1-2 



50 



250 



70 



2-7 



50 



243 



63 



20 



50 



235 



55 



1-4 



60 



250 



70 



2-7 



60 



246 



66 



2-2 



60 



238 



58 



16 



70 



251 



71 



29 



70 



246 



66 



2-2 



70 



240 



60 



17 



80 



253 



73 



3-3 



80 



247 



67 



2-4 



80 



241 



(n 



1-8 



90 



253 



73 



33 



90 



217 



67 



24 



90 



242 



62 



1-9 



2 K 2 



