While investigating this latter subject, Sir Benjamin paid particular attention to the construction of grates and fireplaces, and to the scientific properties of light and heat. He so improved the methods of heating apartments and of cooking food, as to produce a saving in the precious element of heat varying from one-half to seven-eighths of the fuel previously consumed; so that it was wittily said, that he would never rest satisfied until he had cooked his dinner with his neighbours' smoke. To him also is the honour due of being the first to explain the manner in which heat is propagated in fluids. In requital of these important services to the Bavarian state, Thompson was decorated with two orders of Polish knighthood; he also received the appointments of member of the Council of State and lieutenant-general in the army, was created commander-in-chief of the general staff, minister of war, and superintendent of the police of the electorate, and was finally, in 1790, raised to the dignity of Count of the Holy Roman Empire, by the title of Count Rumford, in memory of the American village where he had formerly officiated as schoolmaster. The scientific part of the community also showed their esteem for him, by electing him a member of the Academies of Munich and Manheim; and in 1787, when on a visit to Prussia, he was chosen a member of the Academy of Sciences at Berlin. When the advance of the French army under Moreau compelled the Elector to quit his capital, Count Rumford was for a short time placed at the head of the Regency, and in this capacity succeeded in the arduous task of freeing the Bavarian state from foreign invasion. This important service increased Rumford's reputation with the Elector and the people, and he was permitted to settle one-half of the pension which he enjoyed on his daughter, to be paid during her lifetime.