John P. Holland was not the only inventor who responded to the invitation of the United States navy department to submit designs for a proposed submarine boat in 1893. That invitation had been issued and an appropriation of $200,000 made by Congress on the recommendation of Commander Folger, chief of ordnance, after he had seen a trial trip on Lake Michigan of an underwater boat invented by Mr. George C. Baker. This was an egg-shaped craft, propelled by a steam engine on the surface and storage-batteries when submerged, and controlled by two adjustable propellers, mounted on either side of the boat on a shaft running athwartship. These screws could be turned in any direction, so as to push or pull the vessel forward, downward, or at any desired angle. Mr. Baker submitted designs for a larger boat of the same kind, but they were not accepted. The third inventor who entered the 1893 competition was Mr. Simon Lake, then a resident of Baltimore. He sent in the plans of the most astonishing-looking craft that had startled the eyes of the navy department since Ericsson’s original monitor. It had two cigar-shaped hulls, one inside the other, the space between being used for ballast-tanks. It had no less than five propellors: twin screws aft for propulsion, a single screw working in an open transverse tunnel forward,[12] to “swing the vessel at rest to facilitate pointing her torpedos,” and two downhaul or vertical-acting propellers “for holding vessel to depth when not under way.” These were not placed on deck, as on the _Nordenfeldt II_, but in slots in the keel. Other features of the bottom were two anchor weights, a detachable “emergency keel,” and a diving compartment. On deck were a folding periscope and a “gun arranged in water-tight, revolving turret for defense purposes or attack on unarmored surface craft.” There were four torpedo tubes, two forward and two aft, according to the modern German practice. The motive-power was the then usual combination of steam and storage batteries. But the two remaining features of the 1893 model Lake submarine were extremely unusual. [Illustration: Courtesy International Marine Engineering. Lake 1893 Design as Submitted to the U. S. Navy Department.] Instead of one pair of horizontal rudders, there were four pairs, two large and two small. The latter, placed near the bow and stern, were “levelling vanes, designed automatically to hold the vessel on a level keel when under way”; while the larger ones were called “hydroplanes” and so located and designed as to steer the submarine under, not by making it dive bow-foremost but by causing it to submerge on an even keel. How this was to be accomplished will be explained presently. The other new thing about the Lake boat was that it was mounted on wheels for running along the sea-bottom. There were three of these wheels: a large pair forward on a strong axle for bearing the vessel’s weight, and a small steering-wheel on the bottom of the rudder.