The hydroelectric station uses water from Gatun Lake for driving three turbo-generators of 2,000-kilowatt capacity each, which supply electricity for the operation of the lock and spillway machinery, the terminal shops and adjacent facilities, and for the lighting of the locks and the ca.n.a.l villages and fortifications. Transmission over the Zone is effected through four substations and a connecting high voltage transmission line which follows the main line of the Panama Railroad.

[Ill.u.s.tration: SUBMARINES USED IN DEFENDING THE PANAMA Ca.n.a.l

The vessels here shown are used in defense of the Pacific side of the ca.n.a.l. They appear as anch.o.r.ed in the new concrete docks at Colon, preparatory to their pa.s.sage through the ca.n.a.l, after having made the longest sea voyage then on record for submarines.

_Copyright by Underwood & Underwood, N. Y._]

[Ill.u.s.tration: _Copyright by the International News Service._

THROUGH THE PANAMA Ca.n.a.l

The U. S. battleship "Ohio" in the east chamber of the Pedro Miguel Locks. On the left is seen the electric locomotive used in drawing vessels through.]

[Ill.u.s.tration: LADDER DREDGE, PANAMA Ca.n.a.l]

[Ill.u.s.tration: SUCTION DREDGE, PANAMA Ca.n.a.l

The upper view shows a ladder dredge, which operates by means of buckets on a continuous chain, dipping the contents of the buckets into the scow which lies alongside. The lower view shows a suction dredge, which operates on soft mud or sands, pumping the discharge through the pipe seen at the left of the ill.u.s.tration. The pipe may be carried to any desired point and used for filling.]

[Ill.u.s.tration: _Copyright, C. H. Graves Co._

GATUN LOCKS

A. Sea-level section of ca.n.a.l, seven miles long, from Atlantic Ocean to Gatun Locks, where by a series of three locks vessels are raised to Gatun Lake, eighty-five feet above sea level. B. Small area of land dredged away as soon as Gatun Locks were completed. C. Electric towing motor, four of which tow each vessel entirely through the locks. They run on cog rail along the lock walls. D. Lock gate under construction.

E. Floor of first lock from Atlantic side. Note holes in floor for admitting the water. F. Lock for vessels coming from Pacific side. G.

Base on which concrete posts were erected for electric lights. A row of lights on all sides of the locks making operation at night as safe as day. H. Incline from locks of different levels up and down which the towing motors run on cog rails.]

[Ill.u.s.tration: GAILLARD CUT LOOKING SOUTH FROM BEND IN EAST BANK NEAR GAMBOA

The train and shovel are standing on the bottom of the cut. The water in the drainage ca.n.a.l is about ten feet below the bottom of the ca.n.a.l, or at elevation +30.]

[Ill.u.s.tration: A CYLINDRICAL VALVE MACHINE, MOTOR AND LIMIT SWITCH

This machine is one of many which are used to regulate the flow of water to the locks. All valves are controlled from a central operating station on each of the three sets of locks. The limit switch automatically shuts off the power and stops the motor when the valve is entirely open or shut.]

[Ill.u.s.tration: CUCARACHA SLIDE ATTACKED BY A FLEET OF DREDGES

This great slide was the source of much trouble to the engineers. At one time it entirely blocked the ca.n.a.l at the narrow point shown in this photograph, but the seven dredges of the ladder, suction and dipper type, made short work of cutting the 150-foot channel shown here, and then proceeded with the work of entirely clearing the cut. The view looks north from the slide past Gold and Contractor's Hills.

_Copyright by Underwood & Underwood, N. Y._]

[Ill.u.s.tration: STEAM SHOVEL BURIED UNDER FALL OF ROCK]

[Ill.u.s.tration: THE GREAT GAILLARD CUT

At this point the ca.n.a.l is cut through what is practically a mountain range. The material excavated consisted largely of rock and formed one of the hugest engineering problems in the world's history. The cut is nine miles long, 300 feet wide, 272 feet greatest depth and required the excavation of 100,000,000 cubic yards of material.]

Gatun Lake, impounded by Gatun Dam, has an area of 164 square miles when its surface is at the normal elevation of eighty-five feet above sea level, and is the largest artificially-formed lake in the world. The area of the water-shed tributary to the lake is 1,320 square miles.

During the rainy season, from April to the latter part of December, the run-off from this basin exceeds considerably the consumption of water, and the surplus is discharged through the spillway of Gatun Dam. Toward the end of the rainy season the surface of the lake is raised to about eighty-seven feet above sea level, in order to afford a surplus or reserve supply to keep the channel full to operating depth during the dry season, in part of which the consumption and evaporation are in excess of the supply. It is calculated that when this level has been attained at the beginning of the dry season the reserve is sufficient to a.s.sure a surface elevation of at least seventy-nine feet at the end of the dry season in spite of the consumption at the hydroelectric station, and allowing forty-one pa.s.sages of vessels through the locks each day with the use of the full length of the chambers, or fifty-eight lockages a day when the shorter sections of the chambers are used and cross filling is employed, which would usually be the case. This is a greater number of lockages than can be made in one day.

[Ill.u.s.tration: STEAM SHOVEL LOADING ROCK

These great machines, which are able to dig out and load several tons of material at each operation, made the rapid progress in digging the ca.n.a.l possible.]

Gigantic Obstacles.

The greatest difficulty encountered in the excavation of the ca.n.a.l was due to slides and breaks which caused large ma.s.ses of material to slide or move into the excavated area, closing off the drainage, upsetting steam shovels and tearing up the tracks. The greatest slide was at Cucaracha, and gave trouble when the French first began cutting in 1884.

Though at first confined to a length of 800 feet, the slide extended to include the entire basin south of Gold Hill, or a length of about 3,000 feet. Some idea of the magnitude of these slides can be obtained from the fact that during the fiscal year 1910 of 14,921,750 cubic yards that were removed, 2,649,000 yards, or eighteen per cent, were from slides or breaks that had previously existed or that had developed during the year.

[Ill.u.s.tration: ONE OF THE GUARD GATES, GATUN LOCKS, PANAMA Ca.n.a.l

Each lock is provided with four gates. This shows the method of construction, the gate being only partially finished.]

[Ill.u.s.tration: GATUN UPPER LOCKS, EAST CHAMBER

The view is looking north from the forebay showing the upper guard gates and emergency dam.]

The one greatest undertaking of the whole excavation was the Gaillard Cut. Work had been in progress on this since 1880, and during the French control over 20,000,000 cubic yards were removed. On May 4, 1904, when the United States took charge, it was estimated that there was left to excavate 150,000,000 cubic yards. Some idea of the size of this big cut may be formed from the fact that this division has within its jurisdiction over 200 miles of five-foot-gage track laid, about fifty-five miles of which is within the side slopes of the Gaillard Cut alone.

Gatun Dam.

The great dam at Gatun is a veritable hill--7,500 feet over all, 2,100 feet wide at the base, 398 feet through at the water surface, and 100 feet wide at the top, which is 115 feet above sea level. The dimensions of the dam are such as to a.s.sure that ample provision is made against every force which may affect its safety, and while it is made of dirt, a thing before unheard of, it is of such vast proportions that it is as strong and firm as the everlasting hills themselves.

Fluctuations in the lake due to floods are controlled by an immense spillway dam built of concrete. The front of the dam is the arc of a circle 740 feet long with fourteen openings which, when the gates are raised to the full height, permit a discharge of 140,000 cubic feet per second. The water thus discharged pa.s.ses through a diversion channel in the old bed of the Chagres River, generating, by an enormous electric plant, the power necessary for operating the locks.

The locks of the ca.n.a.l are in pairs, so that if any lock is out of service navigation will not be interrupted, also, when all the locks are in use the pa.s.sage of shipping is expedited by using one set of locks for the ascent and the other for descent. These locks are 110 feet wide and have usable lengths of 1,000 feet. The system of filling adopted consists of a culvert in each side wall feeding laterals from which are openings upward into the lock chamber. The entire lock can be filled or emptied in fifteen minutes and forty-two seconds when one culvert is used and seven minutes and fifty-one seconds, using both culverts. It requires about ten hours for a large ship to make the entire trip through the ca.n.a.l.

Meeting all Emergencies.

Many extraordinary feats of engineering were accomplished to overcome the difficulties presented. Special contrivances, wonderful in their operation, were invented to meet exigencies and emergencies.

The first and greatest problem attempted by the United States was to make the Ca.n.a.l Zone healthful. This strip of land from ocean to ocean abounded in disease-breeding swamps and filthy habitations unfit for human beings. The death-rate was appalling and the labor conditions terrible. During the first two and a half years, therefore, all energies were devoted to ridding the Isthmus of disease by sanitation, to recruiting and organizing a working force and providing for it suitable houses, hotels, messes, kitchens and an adequate food supply. This work included clearing lands, draining and filling pools and swamps for the extermination of the mosquito, the establishment of hospitals for the care of the sick and injured and the building of suitable quarantine quarters. Munic.i.p.al improvements were undertaken in Panama and Colon and the various settlements in the Ca.n.a.l Zone, such as the construction of reservoirs, pavements and a system of modern roads. Over 2,000 buildings were constructed besides the remodeling of 1,500 buildings turned over by the French company.

[Ill.u.s.tration: LOCK GATE OPERATING MACHINERY

_Photograph, Underwood & Underwood, N. Y._

The great gear wheel, known as a "bull wheel," is connected with one leaf of the gate on the right by means of a strut so that revolving the bull wheel by means of an electric motor through a train of gears results in opening or closing the gate.]

[Ill.u.s.tration: PANAMA, PAST AND PRESENT

Scene showing the repaving of one of Panama's old muddy streets with vitrified brick. Sewers and water pipes were laid throughout the city, resulting in a great reduction of disease.]

It was only after all this preliminary sanitation was accomplished that the real work of digging the ca.n.a.l could go forward with any hope of success. These hygienic conditions had the result of making the Ca.n.a.l Zone one of the most healthful spots in the world, and work on the ca.n.a.l became so popular that it was no longer necessary to enlist recruits from the West Indies, the good pay, fair treatment and excellent living conditions bringing thousands of laborers from Spain and Italy. The greatest number employed at any one time was 45,000, of which 5,000 were American.