126 



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[Jan. 11 



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this method. Subjoined is one of the plates produced rolled to 1 mm. 

 thick, measuring 90 cm. x 75 cm. and weighing 8 ■ 700 kilogrammes. 

 Trimming the rough edges from the plate about 1 cm., the results 

 came out as under, showing a constancy of 925 nearly all over the 

 plate. I have drawn a line where the only wave of lower variation 

 occurs. 



