After the air-tight doors have been closed the men who serve these guns will go into action in space-suits, breathing the air around them but having the suits fitted with automatic valves that will close down the moment the compartment begins to lose air. Damage-control parties will have special apparatus for patching holes--probably quick-drying viscous plastics with a silicone base, because of their imperviousness to temperature changes. What about fire controls? The calculations for them will be arduous because of the distances and speeds involved. But Dr. John D. Clark has pointed out that two space-ships engaged in a fight, no matter what courses they are traveling with relation to the Sun or the planets, are in a single plane with relation to each other and so are all the projectiles fired by both of them. This plane may tilt violently as they maneuver but at the moment of firing the line from gun to target, or predicted position of target, is a perfectly flat and straight line. This is a much easier ballistic problem than in any Earthly firing, where gravity, air resistance and for long ranges even the curvature and rotation of the Earth must be considered. The guns will certainly have automatic radar controls and a high rate of fire. The only trouble is that the calculations fed into the controls will have to be made at lightning speeds, in micro-seconds--which means electronic computers. And this brings up another difference between space-warfare and the kind we know, though it may extend to war on Earth. It is possible to make an electronic computer non-functional by overloading it with data or to drive it electronically insane by feeding it undesirable data. Space-warfare is therefore bound to include all sorts of decoy devices--small metal balloons have been suggested--that will register on the enemy's radar as space-ships and set his guns swinging wildly or firing at phantoms. The only type of ship to which all that has been said does not apply is the space-minelayer. These can be quite small as compared with the battleships, need carry no armor and can use the torpedo-shape for operating from an earth base. Some years ago Malcolm Jameson suggested small iron spheres as mines, strewn along the enemy's path where he would run into them--but the matter is not quite that simple. If the space-minelayer merely dumped the spheres overboard as an Earthly minelayer does they would become part of a new small gravitational system around the minelayer, and would follow her around like Mary's little lamb. The mines of space-warfare will have to be provided with some kind of power that will take them into a predetermined orbit around Earth, the Moon or an asteroid after the minelayer has dropped them. Only enough to set up the orbit, mind--after that they could take care of themselves.