234? 



Instructions for the Scientific Expedition 



heit ; q the relative change of the magnetic moment corresponding 

 to one degree ; then 



-.i^ = j(^_32). 

 m 



Accordingly, the changes of the earth's force will be expressed by 

 the formula 



^ = A:« + jO-32). 



It is not necessary that these reductions should be applied to the 

 individual results, except in cases of marked change, where it is de- 

 sired to trace the progress of the actual phenomena. The results 

 should be recorded as they are observed, in parts of the scale ; and 

 the reductions made in the monthly, or other mean values. 



Table II. contains the arc values of one division of the scale, in 

 each instrument, expressed in decimals of a minute ; as also the same 

 quantities reduced to radius, as the unit by multiplying by the number 

 •0002909. 



Table III. contains the intervals of the axes of the wires corre- 

 sponding to each wheel, in decimals of an inch ; the wire used being 

 that designated in commerce as " silver, fine 6." 



Table II. 



Table III. 



