 The plan of operation selected for me was to have an electrotype mould made from my model , in copper , to serve as a pattern for a cast in iron . The operations of the galvanic battery for this purpose were conducted in the apartments of the chief coiner . The galvanic process failed , my model was destroyed in the operation . I had , however , taken the precaution to make a cast in plaster ... From this cast , as the only alternative , I <unk> [ sic ] a metallic one which , however , was not perfect ; but I thought I should be able to correct the imperfections in the engraving of the die ... this was a laborious task , but seasonably completed , entirely by my own hand . The die then had to be hardened in the coining department ; it unluckily split in the process . 
