Mr. Holland's first submarine boat was built in 1875. It was called a "diving canoe," being only sixteen feet in length and wide enough to hold one man clothed in a diving-suit. Four years later, however, Holland built a larger boat called the _Holland No. 3_ constructed along similar lines to the most recent submarines. This was the first buoyant submarine to be steered up and down by horizontal rudders alone, and may be said to mark an epoch in submarine navigation. But the No. 3 had many defects, and Mr. Holland continued to build and improve new boats, until finally his ninth boat, which is the one familiarly known as the _Holland_, represented a practical form of submarine vessel. This boat was 53 feet 10 inches long, 10 feet 3 inches in diameter, had a displacement of 75 tons, and carried 10 tons of water ballast. The gasoline engine which it used when running at the surface propelled the boat at the rate of seven knots an hour, and it could travel a distance of fifteen hundred miles at this rate of speed with the amount of fuel carried. When submerged it could run a distance of about fifty knots without coming to the surface. In diving, the Holland type of boat takes in sufficient water ballast to lower it to the surface of the water. The horizontal rudders are then brought into use causing it to descend to the desired depth, and keeping it at an approximately uniform distance from the surface while running submerged. By this arrangement the boat can dive very quickly, requiring only a matter of eight or ten seconds for reaching a depth of thirty feet. Record plunges have been made in less time than this. The armament of the Holland boat was originally designed to consist of three tubes, two of which were for throwing aërial torpedoes and shells, and the third for discharging Whitehead torpedoes. One of these aërial guns was placed in the bow, and one in the stem; but later the stern tube was abandoned. The bow gun was designed to discharge projectiles a distance of about one mile, such projectiles weighing something over two hundred pounds and carrying one hundred pounds of gun-cotton. The tube for discharging the Whitehead torpedo was practically the same as the submerged tubes in use at present on battle-ships. Although this _Holland_ is now the type of diving boat most familiar to the majority of people, and the one in use in several navies, it should not be understood that the Holland boats were the only successful submarines constructed up to this time. France and Russia had produced successful diving boats; and in America those invented by Simon Lake, some of which are used for wrecking and salvage work as well as for war purposes, have proved quite as practical as the Hollands. In recent tests of these two types by the United States Government the Holland boats showed themselves to be slightly superior to the Lake boats in certain particulars, but the margin of superiority was a very narrow one.