passage from ocean to ocean need not take more than ten hours, of which the passage of the flight of three locks at Gatun I will take one hour. It is hard to understand. some of the recent statements about risks to ships in lockage, when one remembers that the act of passing through lock gates is safer than the very common act of entering a dry dock, or of passing into the great commercial docks at Liverpool and London, and remembers also that of all the great ship canals of the world, every one except the Suez has locks. The freedom from accidents at the Soo, as compared with the Manchester ship canal, is believed to be due to the provision at the Soo of long, straight approach piers on line with the lock, alongside of which the ship can be brought under control before entering the first gate. Besides similar guide piers at the Isthmus, double gates and strong barriers for preventing a ship in motion. from striking a lock gate are proposed, and beyond this, an emergency gate, by which the flow of water could be stopped if the rupture of a gate threatened the draining of the summit level. THE PROGRESS OF EXCAVATION THE COST So much has been already done that there is now a good basis for estimating the cost of what is yet to be done, and it appears that the total cost of the canal, including the railway and its steamship line, and with no allowance for salvage on the construction plant, is going to be about $360,000,000. The figure of $140,000.000, which became fixed in the popular mind as the estimate of cost for the lock canal, expressly omitted the following items: Payments for the property of the Panama... $40,000,000 10,000,000 Sanitation and zone government, which from the present rate of expenditure will cost about... 27,000,000 Cost of work by United States prior to estimate, in round numbers, about..... 10,000,000 $87,000,000 This amount, added to the $140,000,000, gives a total of $222,000,000, which should properly be taken as the estimate of 1905 for a lock canal. Within the past three years the plans IN THE CULEBRA CUT have been changed, with a probable in- The increased dimensions of the add Smoothing up of Culebra Cut walls with concrete.. A change in the new location of the Panama Railroad adds... Change in breakwater inclosing larger harbor.... Balance to equal recent estimate as above..... $20,000,000 10,000,000 14,000,000 4,000,000 States during the organization of this work; to the fact that surveys and borings on the new features were far from complete at the time of the estimate; and, beyond all this, to the many unforeseen extra items of extra cost attendant on carrying on so great a work in the tropics, many hundreds of miles away from the base of supplies. Causes that have increased the cost of the lock canal would have increased the cost of similar items in a sea-level canal in the same proportion, while in the features 6,000,000 of flood control for the sea-level project the uncertainties of surveys were much greater. 79,000,000 The increase of $79,000,000 not distributed above is due mainly to such causes as working eight hours instead of the customary ten hours upon which the unit costs of the estimates were based; to the higher wages and special inducements, such as six weeks' annual vacation, thirty days' sick leave, family dwellings of a degree of comfort never before attempted in a construction camp; to the scarcity of skilled labor and the boom prices prevailing in the United In one very important feature, that of progress, the canal is being built inside the estimate, and for this all the engineers and the men along the line should receive highest praise. There is manifest all along the line a spirit of earnestness, confidence, and cooperation, and a general wholesomeness of life, which make of this narrow fortythree-mile strip the best great construction camp that the world has ever seen, and one of which every American should be proud. THE SEA-LEVEL CANAL AND THE STRAITS OF PANAMA BY PHILIPPE BUNAU-VARILLA P to a recent date (September, 1905), engineers have been contemplating only two forms of the Panama waterway: the lock canal type and the sea-level canal type. The lock form consists in establishing a series of water levels on both sides of the continental backbone. These levels are united by locks which allow the ships to pass from one level to the other, thanks to the vertical lift of the locks. The central level, or summit level, is fed by the waters of the river Chagres. To this end the Chagres is dammed at a given point in order to retain its flood waters and to form a reservoir, the level of which is that of the summit level of the canal, or higher than the summit level. The only advantage of a lock canal is the economy of time of construction that naturally results from a cut through the continental divide of lesser depth than the one necessary for a sea-level canal. There is no other advantage, and those who claim that there are others can be compared to a surgeon who tries to demonstrate to his patient that a wooden leg is preferable to a natural one. The disadvantages of a lock canal, on the other hand, are of the gravest char acter. First, when in use it may be crippled for a long time by a wrong maneuver of the ponderous war-ships and commercial vessels which will pass through the canal. Second, it may be practically destroyed for years if a dynamite-loaded ship explodes during its passage through the locks. An analogous case actually occurred in the Suez Canal in the accident to the steamship Chatham a few years ago. Third, it may be crippled for a long time with a few sticks of dynamite by a party of desperate men. Fourth, it may be crippled in case of war by attacks from below water by a submarine, or from above by an air-ship. Fifth, it may be crippled for an indefinite time by a severe earthquake bursting its earth dams and damaging the gates. Outside of these dangers, which constitute intolerable risks for the great artery upon the free use of which will depend the naval defense of the United States and the very basis of the life of the millions of people of the west coast of America, there are certain and unavoidable limits to the life of a lock canal. There is a constant increase in the dimensions of war and commercial vessels. Every time a lock canal has been projected the dimensions of the locks have been fixed with a margin which was thought at the time to be ample for all possible future increase in the bulk of ships. Before a few years passed the lock as planned became manifestly obsolete. In the plan made by Commander Lull, of the United States navy, under the direction of President Grant, in 1875, the locks were to have 450 feet length and 65 feet width. In the new Panama Company's project of 1898 the locks were to have 738 feet length and 82 feet width. In the Isthmian Canal Commission's projects of 1901 the locks were to have 740 feet length and 84 feet width. In the Consulting Board's (minority) project of 1906 the locks were to have 900 feet length and 95 feet width. Scarcely three years have elapsed since these dimensions, thought to be final, were fixed, and yet it has now been found necessary to increase the length and width to 1,000 feet and 110 feet respectively. The margin left for increase in the dimensions of ships is inadequate. After the Lusitania and Mauretania, with their 800 feet length and 88 feet width, of the Cunard Line, the White Star Line is now building ships longer and wider. After the Dreadnought, with its 19,000t ons, of the English navy, the United States is building battle-ships of 26,000 tons. Everything points to a further and continuous increase in the length and width of both commercial and naval vessels, which will make the actual lock canal obsolete soon after its construction, if not before its inauguration. But this is not the only limitation of a lock canal. The conditions of the water supply condemn it to an early failure in its work of serving the demands of trade. The actual lock canal project is based upon the plan of collecting on the summit level the greatest possible quantity of water from the Chagres and its tributaries. For this purpose the dam across the Chagres River has been placed at the lowest possible place in the valley, at Gatun, in order to receive into the lake behind the dam all the tributaries of the lower Chagres. The Gatun site is an exceedingly bad location for any dam, on account of the enormous width of the valley (7,700 feet); on account of the slippery and unctuous nature of the marine blue clay, deprived of any supporting power, upon which the huge earth dam will rest; on account of the soft, fissured nature of the clayish sandstone of the hills in the vicinity of Gatun, which are equally unfit to retain the waters of the lake and to furnish the foundations for the heavy masonry work. The safety of the structure, and therefore of the whole canal, has been sacrificed to extend the natural limits of the traffic power of the canal. Several other plans of lock canal of safe construction may be devised, but the water supply and the corresponding traffic limit would be reduced by at least one-third. In spite of the terrible risk accepted in the present plan in order to collect all the water possible for the operation of the canal, it is easy to see that even then the traffic capacity is very limited. When presenting their project in January, 1906, the minority of the Consulting Board stated that with 53 lockages the traffic would be able to reach between 58 and 96 million tons annually, according to the future average size of ships passing through. For such a traffic a discharge of water of 3,978 cubic feet per second is necessary. It is easy to establish, according to the graphical registrations made during fifteen years of the water-flow at Bohio, nine miles above Gatun, that the average discharge in the driest years is 3,384 cubic feet per second there. As the minority of the Consulting Board has admitted that a reduction of twenty per cent should be made in view of possible unforeseen droughts; as, on the other hand, gauges taken in February, March, and April, 1900, at Gatun and at Bohio simultaneously have shown that the flow |