THE original estimated date for the completion of the Panama Canal was January 1st, 1915. The work has advanced so rapidly that it has become apparent that the canal can be used at least a year earlier than this date. In order to determine the approximate time when shipping could pass through, a board was convened during the past year, composed of those charged with the work in progress and contemplated. Announcement was made that concreting of the locks at Gatun would be finished by June 1st, 1912, and the locks on the Pacific side four months later. Assuming that the gates were completed by June 1st, 1913, the contract time, the locks would be ready on that date, if the operating machinery were installed. The Gatun dam, it was estimated, would be finished by the close of the dry season 1912-1913, and if no more material, due to slides, had to be removed than was estimated at the time the board met, it was decided that the Culebra cut would be completed by July 1st, 1913. The exterior channels leading to the canal from the two oceans, it was found, would be sufficiently advanced to pass such shipping that would use the canal, by this same date, July 1st, 1913. The report of Col. George W. Goethals, chairman and chief engineer, shows that progress during tile past year has been eminently satisfactory. At Gatun locks, by the end of the fiscal year, the skeletons of four leaves of the gates were in position for a height of four panels, and those on the east chamber were completely riveted. At all of the locks, fender chains are to be placed 500 feet above and 230 feet below the upper and lower guard gates. When in use, they will be raised to the surface of the water, forming a barrier to the passage of ships. When it is struck by a vessel, the chain pays out against a resistance provided by hydraulic cylinders. The energy of a 10,000-ton ship moving four miles an hour will be absorbed after it strikes the chain before it reaches the gate. Contracts for emergency or movable dams to check the outflow of water should the gates be carried away, have been awarded for $2,238,988, and all of these dams are to be completed by June 15th, 1913. Studies are being made of an electrical plant for operating the canal after completion, which contemplates a hydroelectric station on the Gatun dam, and a steam reserve generating station at the Mirafiores locks. A scheme for lighting the canal has been adopted. It contemplates the use of range lights for establishing the direction on the longer tangents, and of side lights, spaced about a mile apart, to mark each side of the channel. The project calls for the construction of 34 tower beacons of reinforced concrete, 57 beacons, 57 gas buoys, 76 spar buoys, and 7 nun buoys. There will be two parallel sailing lines, marked by range lights, which will be 250 feet apart; so that two passing ships, if on their ranges, will be 250 feet apart, center to center of ships. Atlantic Division. At the Gatun locks the excavation has been completed, except for a small amount at the north end of the lower locks. The concreting plant has shown great efficiency and capacity. The unloading cables have handled 500,550 cubic yards of crushed stone, and 241,858 cubic yards of sand. During the year, 945,525 barrels of cement were received into the storehouse, and in the same time an average of 1).08 of the eight 2-yard mixers furnished a total of 602,851 cubic yards of concrete. The total amount of masonry laid: by the construction plant and by hand at the Gatun locks aggregated 911,137 cubic yards—a rate. of 260.6 cubic yards per hour of service. The cost of the masonry was $6.64 per cubic yard. At the close of the year the masonry for the Gatun locks was 68.34 per cent completed. Over half a million cubic yards of backfilling was placed in the rear of the side walls of all the locks. A total of 31,060 feet of concrete piling was constructed for the foundation of the south middle approach wall, leading to the locks from Gatun Lake. A total amount of 864,033 cubic yards of stone was crushed at the Porto Bella quarry at an average cost of 1.38 cents per yard, and from Nombre de Deos a total amount of 441,919 cubic yards of sand was obtained and transported in barges to Gatun, where it was transferred to the stock pile, at a cost,' in the stock piles, of 1.86 cents per cubic yard. Gatun Dam. The Gatun dam has been formed by building two large rock embankments, and filling in the intervening space by hydraulic sluicing. During the year, on the east portion of the dam, the embankments have been raised from 65 feet to 85 feet above mean tide, and the hydraulic fill has been raised from 51 to 73 feet. On the west portion of the dam, the dry fill has been raised from 35 to 67 feet, and the hydraulic fill from 16 to 57.3 feet. The total increase of material, dry and wet, during the year has been 5,819,056 cubic yards. The cost of this work has been 38 cents for dry fill, and 23 cents for wet fill. The material for dry fill was brought by railway from Culebra 'cut, from the lock site, from Mindi, and from the spillway. The hydraulic fill was obtained from above and below the dam, and was placed by five suction dredges. The dam at the close of the fiscal year was 74 per cent completed. Work on the spillway has proceeded very satisfactorily, and the concrete portion of the work is 66 per cent completed. The channel between Gatun locks and the Atlantic is being attacked at several points, and 423,427 cubic yards have been removed between the locks and the Mindi hills. From the excavation through the Mindi hills 401,511 cubic yards have been removed by hydraulic dredge, and 280,000 cubic yards of earth and rock have been taken out by steam shovel. Between the Mindi hills and deep water in the Caribbean, the sea-going dredge “Caribbean,” two dipper dredges, and three French ladder dredges have removed 4,516,369 cubic yards of earth and 487,038 cubic yards of rock, at a cost of 22 cents per cubic yard. The breakwater leading out from Toro Point has been pushed forward until, at the close of the year, 5,365 feet of double-track trestle had been completed, and 359,890 cubic yards of fill had been dumped from the trestle. Central Division-Culebra Cut. In the central division, the most important construction district is, of course, the great Culebra cut, from which during the fiscal year over sixteen million cubic yards were excavated, leaving, according to estimates of July 1st, 1911, about twenty-four million cubic yards yet to be taken out. The amount remaining has been increased during the year by 4,676,000 cubic yards, this to allow for the enormous slides which have developed, in the removal of which alone during the year, 4,880,000 cubic yards has had to be handled, which is over 30 per cent of the total amount removed from the cut during the year. The magnitude of this problem may be judged from the fact that thus far 10,757,000 cubic yards have been removed from slides, and the estimated amount remaining is nearly six million cubic yards. Col. Goethals states that slides follow the excavation in places where the material is left at a steeper slope than it will assume in it;:; natural state; in which case it sloughs off until the natural slope is reached, and the movement ceases. Experience shows that it is only a question of time when these slides will cease entirely. Six of. the good-sized slides are now quiet, and there is less trouble generally from this cause than at any time since the slides began to move. A gratifying feature of this problem is the fact that, in spite of the enormous increase of 15,000,000 cubic yards of excavation due to slides, the reduction in unit cost, due to the splendid efficiency of the organization, will wipe out the extra cost of the slides, leaving' the original estimate of excavating Culebra sufficient to cover the total cost of the work. The average cost for excavation for the year was 59 cents per cubic yard, and at the close of the year the Culebra cut was 73.75 per cent completed. Pacific Division. The work of this division consists of the construction of the locks and dams at Pedro Miguel and at Mirafiores, and the excavating of a channel between the locks, and from Mirafiores locks to deep water in the Pacific. The total amount of concrete laid in the Pedro Miguel locks at the close of the year was 665,056 cubic yards, and the lock was 79.43 per cent completed. The locks at Mirafiores, so far as the concrete work is concerned, are 19.27 per cent completed. As regards the channel between the locks and the Pacific Ocean, work has advanced satisfactorily between the two locks, and operations are being vigorously pushed upon the section lying between Mirafiores locks and the Pacific Ocean. The dredges operating in the channel during the year were the 2O-inch suction sea-going dredge Culebra, one dipper dredge, and three French ladder dredges. They removed from the channel a total of five and a half million cubic yards at a cost of 25 cents per yard, leaving a total of 4,700,000 cubic yards to be removed, including an estimate for siltage. Towing Locomotives for the Gatun Locks. By studying our front page engraving, it is possible to get a very accurate impression of the Gatun dam, with its spillway through the center, and of the massive concrete locks, through which access will be had to the Gatun Lake. The Gatun locks will be double, one set for ascending, and the other for descending vessels. They will be in three flights,. and will have a total lift of 85 feet—this being the difference between the level of the surface of the lake and mean tide level of the Atlantic at this point. The locks lie some six miles from the Atlantic shore line, and the channel will be tidal up to the lower lock gates, with a small rise and fall of two feet—one above and one below mean level. (At the Pacific end, the rise and fall is 11 feet above and 11 feet below mean tide level. ) The locks are the largest ever constructed, each having a width of 110 feet, and a usable length of 1,000 feet. Entering the canal from the lake, ships will find themselves guarded against running into the locks by fender chains which normally will lie at the bottom of the locks, but when a ship is entering will be stretched across the surface. As a further protection to the gates, there will be guard gates, placed some distance ahead of the main gates. These gates could be wrecked by an over-running ship without destroying the integrity of the canal and letting the water out of the lake. Should a big vessel, becoming unmanageable, enter with such force as to carry away fender chain, guard gates, and the main gates themselves, an emergency dam is provided, by which the entrance to the locks could be closed. This dam consists of a massive swing bridge, which, in case of accident, could be turned so as to lie across the lock entrance. From the over-spanning bridge, a series of massive leaves of plate steel, extending entirely across the lock prism, would be lowered, gradually shutting off the flow of water, from below upward, until the wall of plates extended above lake level, when the entrance would be entirely closed. Ships will not pass through the locks under their own power. Each ship will be taken in hand by four powerful electric locomotives, one off each .bow and one off each quarter. The locomotives will each weigh 70,000 pounds. They will be driven by electric motors, operating gears which will engage a rack rail, and the hawsers from the ship will be attached to the windlasses of the locomotives, which will be provided with friction clutches, that will prevent the drums sustaining a pull of more than 25,000 pounds. The speed of the ships, when in tow of the locomotives, will be not; over two miles per hour. The provision of rack rail traction, aJ;ld the power and number of the locomotives, combined with careful operation, will practically eliminate any' risks to the locks during the passage of vessels. Preserve Your Papers; They Are of Permanent Value BY taking a little trouble, when a paper first comes to hand, it may be preserved to form a permanent and valuable addition to the reading matter with which everyone should be supplied. We furnish a neat and attractive cloth board binder, which will be sent by mail, prepaid, for $1.50. It has good strong covers, on which the name Scientific American or Scientific American Supplement is stamped in gold, and means by which the numbers may be securely held as in a bound book. One binder may thus be made serviceable for several years, and when the successive volumes, as they are completed, are bound in permanent form, the subscriber ultimately finds himself, for a moderate cost, in possession of a most valuable addition to any library, embracing a wide variety of scientific and general information, and timely and original illustrations. Save your papers. To Our Subscribers WE are at the close of another year—the sixty-seventh of the Scientific American's life. Since the subscription of many a subscriber expires, it will not be amiss to call attention to the fact that the sending of the paper will be discontinued if the subscription be not renewed. In order to avoid any interruption in the receipt of the paper, subscriptions should be renewed before the publication of the first issue of the new year. To those who, are not familiar with the Scientific American Supplement a word may not be out of. place. The Scientific American Supplement contains articles too long for insertion in the Scientific American, as well as translations from foreign periodicals, the information contained in which would otherwise be inaccessible. By taking the Scientific American and Supplement the subscriber receives the benefit of a reduction in the subscription pi-ice. 1)98 SCIENTIFIC AM View of Pedro Miguel locks, looking west at intersection of center, and guide walls. The concrete walls are erected by means of the large cantilever crane. Looking north at the upper chamber of the east lock at Gatun. The bridge across the lock in the foreground is being used in connection with the erection of the gates of the lock. The Gatun locks. View showing south hea3 v Bird's eye view of one of the guide walls, looking south, taken from top of a chamber crane. Pedro Miguel locks. View looking through lock along the axil RECENT VIEWS OF 'T] Photographscopyright 1911 lis for lower locks and end of middle lock. A view of one of the cranes at Miraflores. These are used for conveying the stone, sand, etc., from the stock piles to the mixers located in the base of the towers. if the central dividing wall separating the adjacent locks. WORK AT PANAMA y Underwood&Underwood View of Gamboa Bridge, a permanent structure across the Chagres River. The waters of Gatun Lake will back up to about ten feet below this bridge. General view of Pedro Miguel locks, looking south, from the top of a crane that is being dismantled.