producing any very satisfactory results on the experimental crucible, and his operations were again brought to a standstill. A chimney of brick having been substituted for the cast-iron pipe, he was, however, enabled to proceed with his trials. He continued to pursue his experiments in assaying for about two years, during which he had been working entirely after the methods described in books; but, feeling the results still unsatisfactory, he determined to borrow no more from the books, but to work out a system of his own, which should ensure results similar to those produced at the blast-furnace. This he eventually succeeded in effecting by numerous experiments performed in the night; as his time was fully occupied by his office-duties during the day. At length these patient experiments bore their due fruits. David Mushet became the most skilled assayer at the works; and when a difficulty occurred in smelting a quantity of new ironstone which had been contracted for, the manager himself resorted to the bookkeeper for advice and information; and the skill and experience which he had gathered during his nightly labours, enabled him readily and satisfactorily to solve the difficulty and suggest a suitable remedy. His reward for this achievement was the permission, which was immediately granted him by the manager, to make use of his own assay-furnace, in which he thenceforward continued his investigations, at the same time that he instructed the manager's son in the art of assaying. This additional experience proved of great benefit to him; and he continued to prosecute his inquiries with much zeal, sometimes devoting entire nights to experiments in assaying, roasting and cementing iron-ores and ironstone, decarbonating cast-iron for steel and bar-iron, and various like operations. His general practice, however, at that time was, to retire between two and three o'clock in the morning, leaving directions with the engine-man to call him at half-past five, so as to be present in the office at six. But these praiseworthy experiments were brought to a sudden end, as thus described by himself:--