SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON RODS. 227 



Method of Reducing Observations. 



As a typical illustration of the whole work, let us consider the reduc- 

 tion of the observations taken on the largest iron rod used in the long 



TABLE XIII. [Figi-re 15.] 



February 21, 1907. 



Diam. = 1.905 cms. = 3/4 in. Bessemer Steel. 

 Reversals in' Long Coil. 



solenoid. This is the series on Rod No. I, begun on February 21. It 

 usually takes about two days to take a series of observations, and the 

 reductions and plotting of curves take about two or three days 

 more. 



When using the reversal method, the observations were taken under 



