§4. Persons exempt by the laws of the United States are the vice-president, the subordinate executive and all the judicial officers of the government of the United States; members of congress and its officers; custom-house officers and their clerks; post-officers and drivers of mail stages; ferrymen employed at ferries on post-roads; pilots and mariners. §5. By the constitutions of the several states, the governors are made the commanders-in-chief of the militia of their respective states; and by the constitution of the United States, the president is made commander-in-chief of the army and navy of the United States, and also of the militia of the states when called out into actual service. It has already been remarked, (§2,) that the military force of the state is at the command of the executive to protect the government and its citizens. So the president was thought the proper person to have command of the public forces, to execute the laws of the United States, to repel invasion, and to carry on war. Hence the governors and the president are not among the public officers who are exempt from military duty. §6. Persons who, having been duly notified, refuse to appear at military parades, or, appearing without being equipped as the law directs, are tried by a military court, called _court martial_, consisting usually of three military officers, or of such other persons as may be appointed according to the law of the state. If the persons tried do not show good cause for their delinquency, they are fined in such sums as the law prescribes. In certain cases courts may consist of more than three members. §7. The highest militia officer, except the governor, is the _adjutant-general_ of the state; who keeps a list of all the higher commissioned officers, containing the dates of their commissions, their rank, the corps (pronounced _core_) they belong to, the division, brigade, and regiment, and their places of residence. He distributes all orders from the commander-in-chief (the governor,) to the several divisions; attends public reviews where the commander-in-chief reviews the militia; and obeys all orders from him relative to carrying into execution the system of military discipline established by law. §8. There is also in some states a _commissary-general_, who has the care of the arsenals and magazines, and the articles deposited in them. An _arsenal_ is a building in which are kept cannon, muskets, powder, balls, and other warlike stores; all of which are to be kept in repair and ready for use.