| Description | The scale coefficients of the bifilar magnetograph at Kew’ determined with the first magnet. The magnet was used from December 1857 to April 1858. Includes the temperature coefficient ‘determined’ by Mr [John] Welsh. Description of the method of determining the scale coefficient. Discussion regarding the value of K. Refers to deflection and distances. Remarks ‘the method of deflection is no doubt the most correct method of determining the value of K’. Includes the value of K in December 1857 and April 1858. |