It is impossible to attempt a discussion here of the exact constructional details of these parts of a ship; but in order to illustrate briefly what is the purpose of having bulkheads, we may take the Titanic as an example. She was divided into sixteen compartments by fifteen transverse steel walls called bulkheads. [Footnote: See Figures 1 and 2 page 116.] If a hole is made in the side of the ship in any one compartment, steel water-tight doors seal off the only openings in that compartment and separate it as a damaged unit from the rest of the ship and the vessel is brought to land in safety. Ships have even put into the nearest port for inspection after collision, and finding only one compartment full of water and no other damage, have left again, for their home port without troubling to disembark passengers and effect repairs. The design of the Titanic's bulkheads calls for some attention. The "Scientific American," in an excellent article on the comparative safety of the Titanic's and other types of water-tight compartments, draws attention to the following weaknesses in the former--from the point of view of possible collision with an iceberg. She had no longitudinal bulkheads, which would subdivide her into smaller compartments and prevent the water filling the whole of a large compartment. Probably, too, the length of a large compartment was in any case too great--fifty-three feet. The Mauretania, on the other hand, in addition to transverse bulkheads, is fitted with longitudinal torpedo bulkheads, and the space between them and the side of the ship is utilised as a coal bunker. Then, too, in the Mauretania all bulkheads are carried up to the top deck, whereas in the case of the Titanic they reached in some parts only to the saloon deck and in others to a lower deck still,--the weakness of this being that, when the water reached to the top of a bulkhead as the ship sank by the head, it flowed over and filled the next compartment. The British Admiralty, which subsidizes the Mauretania and Lusitania as fast cruisers in time of war, insisted on this type of construction, and it is considered vastly better than that used in the Titanic. The writer of the article thinks it possible that these ships might not have sunk as the result of a similar collision. But the ideal ship from the point of bulkhead construction, he considers to have been the Great Eastern, constructed many years ago by the famous engineer Brunel. So thorough was her system of compartments divided and subdivided by many transverse and longitudinal bulkheads that when she tore a hole eighty feet long in her side by striking a rock, she reached port in safety. Unfortunately the weight and cost of this method was so great that his plan was subsequently abandoned.