Copy letter from Robert William Frederick Harrison to A P Trotter, The Board of Trade 'Dear Sir, Me Mather, a Fellow of the Royal Society, who has a paper here to-morrow on "Comparison of the Board of Trade ampere standard balance with the British Association current weigher", as well as on the E M F of the normal Cadium Cell, is desirous that you should attend the meeting, and I am to say that if you care to do so you will be welcome. The meeting begins at 4.30 and there is tea at 4 o'clock.' 25 March 1908