Copy letter from Robert William Frederick Harrison to The London Stereoscopic Co Ltd 'The National Physical Laboratory have received permission to reprint the paper on "The constitution of the alloys of aluminium and zinc" by Messrs Rosenhain & Archbutt recently published in the Philosophical Transactions of the Royal Society, and for which you prepared the plates. The Laboratory will be marking a requisition on you for the pulls of these plates, and I shall therefore be much obliged by your keeping them [on the stone] in anticipation of this further order.' 3 October 1911