=Unloading mines.=—Should any of the mines be loaded with dynamite the utmost care must be exercised in unloading them. (See p. 76.) Some contrivance must be rigged up so that the first few turns of the compound plug may be accomplished by the operator at a distance, as there is great liability of explosion, due to leakage of nitroglycerin into the screw threads. After the compound plug is removed the precautions to be observed are given in Appendix No. 1. Should the mine be loaded with guncotton or trotol, no danger is to be apprehended in unloading; the usual precautions in handling high explosives must, of course, be observed. CHAPTER VIII. THE MINE COMMAND. A mine command consists of the mine groups and rapid-fire batteries specifically assigned for their protection, which are controlled by a single individual. The mine commander is in direct command of the elements of the mine defense during drill and action. His station is at the mine primary, which is connected by telephone to the battle commander’s station. He bears the same relation to the battle commander as do the fire commanders, and his duties are similar to theirs. The mine commander is responsible that the property officer requests for all matériel necessary to carry out the approved scheme for mining the harbor; he is responsible, further, that the property officer keeps this matériel in proper condition for immediate service. The senior company officer of the mine command is the property officer and obtains from the district artillery engineer all necessary matériel for the mine defense. He has direct charge of the storeroom, cable tanks, loading room, wharves, boats, boathouses, and mining casemate. The personnel of the mine companies are subject to his orders for service in connection with caring for and maintaining this matériel. The officers of the companies of the mine command will be assigned by the mine commander in accordance with their special fitness. The enlisted personnel of mine companies will be divided into sections, detachments, and details, as follows: (_a_) Fire-control and power section. (_b_) Planting and loading section. (_c_) Gun and ammunition sections. (_d_) Reserve section. These will be subdivided as follows: