Letter from Matthew O'Brien, regarding his paper 'Researches in symbolical physics. On the translation of a directed magnitude as symbolised by a product. The principles of statics established symbolically' Apologises for the late reply. Is happy to rewrite the paper, which should take about six weeks. Asks if a copy of the paper could be left for him at Kings College, as he does not have a copy and would like to refer to it during rewriting. Subject: Physics, Mathematics [Published in the 'Proceedings of the Royal Society of London'] 1 March 1852