The fourth photograph shows the projectile emerging from the smoke-cone about thirty feet above the muzzle of the mortar. The men who fire these mortars from the mortar-pits never see the distant target or vessel they are firing at, but point their mortars according to directions transmitted to them (usually by telephone) from observers at distant stations. And so great a degree of precision has been attained that, on certain practice occasions at Hampton Roads, a record of nine hits out of ten shots has been scored on a moving target five miles out in the ocean. This picture shows the smoke-cone as first seen by the human eye.] Captain Behr’s general idea was to utilize some phenomena connected with the discharge to actuate, by electrical connections, a mechanism that would work a rapid shutter in a properly placed camera. The phenomenon of concussion was tried first--the smash of air against a little swinging door; but this was much too slow. The projectile was hundreds of yards away before the camera had registered its picture. And that chance was gone! [Illustration: THE PROJECTILE HIGH IN THE AIR In the fifth photograph the projectile is seen entirely clear of the smoke-cone and well started on its long flight. Climbing into the sky at this steep angle, it will reach a height of from three to six miles before it begins to descend. There are harbors on our coasts guarded by so many guns and mortars that if these were fired simultaneously they could hurl against a given small area a converging rain of projectiles aggregating more than fifty tons in their combined mass. A minute later they could hurl another fifty tons against the same small area; and so on as long as the ammunition lasted.] In the next trial, several months later, Captain Behr arranged to have the electrical connections made or broken by the movement of the gun-carriage itself in recoiling; but the result was unsatisfactory. Nor was he more fortunate at the succeeding target practice, when, having placed the apparatus farther forward on the parapet, he had the camera demolished by the force of the concussion and several blades of the rapid shutter broken. He was satisfied, now, that his effort to actuate the camera mechanism from the gun-carriage would never give the requisite precision in results, and he saw that he must work with a device functioning more reliably.