Faraday to George Biddell Airy   20 May 1847

Royal Institution | 20 May 1847

My dear Airy

I wish I could give you an opinion worth the postage of your letter¹ but indeed I have not one of such value in this case. I do not see any reason why a pure metal should be particularly free from internal change of its particles and on the whole should rather incline to the hard alloy than to soft copper & yet I hardly know why[.] I suppose the labour would be too great to lay down the standard in different metals & substances and yet the comparison of them might be very important hereafter for 20 years seems to do or tell a great deal in relation to standard measures.

I am My dear Sir | Very Truly Yours | M. Faraday

G.B. Airy Esq | &c &c &c