[Illustration: THE FRAMING AND SOME OF THE DECK BEAMS OF THE IMPERATOR, AS SEEN FROM INSIDE THE BOW, BEFORE THE OUTSIDE PLATING WAS RIVETTED ON] In a previous chapter it was shown that when the _Titanic_ is being driven at a speed of 21 knots, she represents an energy of over 1,000,000 foot-tons. If this enormous energy is arrested, or sought to be arrested, by some rigid obstruction, whether another ship, a rock, or an iceberg, the delicate outside skin will be torn like a sheet of paper. It was shown in Chapter IV that protection against flooding of a ship through damage below the water-line is obtained by subdividing the hull into separate watertight compartments, and that, roughly speaking, the degree of protection is proportionate to the extent to which this subdivision is carried. Applying this to the _Titanic_, we find that she was divided by 15 transverse bulkheads into 16 separate compartments. But, in this connection it must be noted that these bulkheads did not extend through the whole height of the ship to the shelter deck, as they did in the case of the _Great Eastern_, and therefore it cannot be said that the whole of the interior space of the hull received the benefit of subdivision. As a matter of fact, only about two-thirds of the total cubical space contained below the shelter deck was protected by subdivision. Water, finding its way into the ship above the level of the decks to which the bulkheads were carried, was free to flow the whole length of her from stem to stern. Furthermore, the value of the subdivision below the bulkhead deck depends largely upon the degree to which this deck is made watertight. If the deck is pierced by hatchways, stairways, and other openings, which are not provided with watertight casings and hatch covers, the integrity of the deck is destroyed, and the bulkhead subdivision below loses its value. It was largely this most serious defect--the existence of many unprotected openings in the bulkhead deck of the _Titanic_--that caused her to go down so soon after the collision. [Illustration: THIS DRAWING SHOWS HOW THE PLATING OF THE INNER BOTTOM OF SUCH A SHIP AS THE TITANIC MAY BE CARRIED UP THE SIDE FRAMES TO FORM AN INNER SKIN]