Lock canal advocates say a narrow sea-level canal could easily be obstructed by an obstacle placed in the channel; sea-level advocates say that a bag of dynamite under the lock-gates could put the canal out of service. Both statements are true but the essential element of difference is in degree. The obstruction in the channel would be no real injury to the canal at all: it would necessitate merely a few days work at the most for its removal. An injury to the locks, however, might readily mean draining of the summit lake and the destruction of all between it and the sea not to speak of the indefinite period required for reconstruction. The point is that it is practically impossible for man to seriously injure a sea-level canal; it is easily possible for him to so injure a lock canal. However, lock canals can be more readily defended in time of war because the points of attack are known beforehand. A very serious objection to the lock type is that it cannot be readily enlarged. The locks are to be 1,000 feet long and 110 feet wide. This is ample for the present but indications are that future needs will be far greater. If they do become greater the Panama Canal will be an inefficient servant and will come far short of fulfilling the purpose which prompted its building. The sea-level canal could be enlarged by dredges without stopping traffic through it, but with a lock canal it is different. When the locks as constructed become inadequate the only way to increase their capacity is to shut down the canal for years while new and larger ones are being built. It is unquestionably true that the ideal canal is a sea-level canal 500 feet to 600 feet wide. This is of the type known as the “Straits of Panama” proposed by Philippi-Bunau-Varilla to the consulting board in 1905. There is a growing feeling that this plan is the one which will ultimately be adopted for the completion of the canal. It contemplates the construction of a lock canal to be finally converted into a sea-level canal. The locks were to be constructed so that as the levels were deepened by dredging they could be eliminated, navigation continuing during the enlargement. The material removed by the dredges was to be deposited in the lake formed by a dam at Gamboa. The plan was carefully considered and finally rejected because of the excessive time and cost involved. It is interesting to note what the author of the plans states in regard to it. He says in part, “It is easy to see from the records that this rejection was purely based on the false assumption that the transformation of rock into dredgable ground would cost $2.35 (per cubic yard), when it has since been officially demonstrated to cost eleven times less in the Suez Canal and eighteen times less in the Manchester Canal.”