It was therefore decided to now test the powers of the crabs. Signals were made from Repeller No. 1 to Crab A, which had been lying with the larger vessel between it and the enemy. These signals were made by jets of dense black smoke, which were ejected from a small pipe on the repeller. These slender columns of smoke preserved their cylindrical forms for some moments, and were visible at a great distance by day or night, being illumined in the latter case by electric light. The length and frequency of these jets were regulated by an instrument in the Director's room. Thus, by means of long and short puffs, with the proper use of intervals, a message could be projected into the air as a telegraphic instrument would mark it upon paper.

In this manner Crab A was ordered to immediately proceed to the attack of the Scarabaeus. The almost submerged vessel steamed rapidly from behind her consort, and made for the British man-of-war.

When the latter vessel perceived the approach of this turtle-backed object, squirting little jets of black smoke as she replied to the orders from the repeller, there was great amazement on board. The crab had not been seen before, but as it came rapidly on there was no time for curiosity or discussion, and several heavy guns were brought to bear upon it. It was difficult to hit a rapidly moving flat object scarcely above the surface of the water; and although several shot struck the crab, they glanced off without in the least interfering with its progress.

Crab A soon came so near the Scarabaeus that it was impossible to depress the guns of the latter so as to strike her. The great vessel was, therefore, headed toward its assailant, and under a full head of steam dashed directly at it to run it down. But the crab could turn as upon a pivot, and shooting to one side allowed the surging man-of-war to pass it.

Perceiving instantly that it would be difficult to strike this nimble and almost submerged adversary, the commander of the Scarabaeus thought it well to let it alone for the present, and to bear down with all speed upon the repeller. But it was easier to hit the crab than to leave it behind. It was capable of great speed, and, following the British vessel, it quickly came up with her.

The course of the Scarabaeus was instantly changed, and every effort was made to get the vessel into a position to run down the crab. But this was not easy for so large a ship, and Crab A seemed to have no difficulty in keeping close to her stern.

Several machine-guns, especially adopted for firing at torpedo-boats or any hostile craft which might be discovered close to a vessel, were now brought to bear upon the crab, and ball after ball was hurled at her. Some of these struck, but glanced off without penetrating her tough armour.

These manoeuvres had not continued long, when the crew of the crab was ready to bring into action the peculiar apparatus of that peculiar craft. An enormous pair of iron forceps, each massive limb of which measured twelve feet or more in length, was run out in front of the crab at a depth of six or eight feet below the surface. These forceps were acted upon by an electric engine of immense power, by which they could be shut, opened, projected, withdrawn, or turned and twisted.

The crab darted forward, and in the next instant the great teeth of her pincers were fastened with a tremendous grip upon the rudder and rudder-post of the Scarabaeus.

Then followed a sudden twist, which sent a thrill through both vessels; a crash; a backward jerk; the snapping of a chain; and in a moment the great rudder, with half of the rudder-post attached, was torn from the vessel, and as the forceps opened it dropped to leeward and hung dangling by one chain.