Letter from John Joly, Trinity College, Dublin, to Dugald Clerk, Chairman of Engineering Sub-committee of the Royal Society, Notes that very few men can experiment with explosives, rendering the development of his ideas impossible: 'in view of what is now happening, this is a grave, indeed, a despairing conclusion to come to'. Asks if further drawings or a working model might modify the committee's judgement. 25 February 1915