July 27th, the journey was ended. They were home again. [ applause ] ahead lay three weeks of isolation, medical tests and mission debriefings. Then visits to major cities of america and abroad. The details of their unique mission would be relived and reremembered so others might learn what they had learned and that future travellers in space might build upon their experience. The rock and soil samples brought back would be examined and analyzed by scientists in many lands. They would reveal new insights in to the origin and age and the composition of the moon. And perhaps new knowledge of the earth as well. Already experiments left on the moon were sending back revealing new information. The mission was successfully completed. The eagle had landed the first men on the moon and columbia had returned them safely to the earth. Whatever mans journey tomorrow across the ocean of universe history will remind him that apollo 11 was mankinds First Encounter with a new world. Up next on American History tv the story of the construio construction of the hoover dam. That will be followed by a 1960 interview with Herbert Hoover who discussed his life beyond presidency. Later u. S. Army captain William Johnston on his work of the army of vietnam in the 1960s and a new deal promotional video in 1938 all ahead here on cspan 3. Here is a look at whats ahead this Labor Day Weekend on American History tv. Saturday at 6 00 p. M. Eastern, the civil war and the Atlanta Campaign when the city fell to the union in september of 1864. Coming up sunday at 6 30 supreme Justice John Roberts on the history of the magna carta. All of that coming up this weekend on American History tv here on cspan 3. Each week American History tvs real america brings you archival films that help to tell the story of the 20th century. In an attempt to control the Colorado Rivers flooding and provide water to arid regions of california and arizona, the u. S. Began construction in 1931. The project employed over 21,000 workers and was completed ahead of schedule. Next a 1955 department of the interior film about the planning and building of hoover dam. The story explains the engineering feats necessary for the structure. This is the story of hoover dam, one of americas seven modern Civil Engineering wonders. Build a dam in the wilderness and the world will beat a path to it. For many centuries this was a lonely canyon, unseen and untouched by man. Scorched by a desert sun. Scolded by an angry river slashing its way to the mother sea. Now it lies peaceful and silent except for the gentle hum of a hydroelectric power plant, the bubbling up of water as it leaves turbines, cheerful sounds of america and world on the move to see this pioneer multipurpose Reclamation Project man built in black canyon. Millions come to this once desolate spot to see this engineering wonder, to hear the story of hoover dam. Ladies and gentlemen, were now standing on the powerhouse ramp, 560 feet below the top of the dam. This is black canyon where nevada and arizona meet, where the Colorado River once flowed uncontrolled. Here is where man conquered this mighty river placing a concrete yolk about its neck to harness its tremendous water and power. Through the ages the river has gathered to the snow rivets of the rockies flowing southwestward to the pacific ocean, gouging great canyons, piling up great deltas of silt in the valleys. Early settlers were at the merscy of this untamed giant. Melted snow from the mountains each spring swelled the Colorado River into a raging torrent. Flooding fertile valleys along itsmcmmo n banks. Destroying farmlands, homes and cities. In 1905, the colorado cut through its banks below the Mexican Border and for two years poured unchecked into the saltin sink forming an inland sea. After each springs flood when the river had spent its fury it dried a trickle, crops withered and died. All living things suffered. Settlers along the river were discouraged. And aroused. Some gave up and went elsewhere. Others stayed to fight. The river had to be regulated. Controlled in a year round flow if they were to succeed. No more floods. No more droughts. Arthur powell davis first reclamation director and chief engineer understood their problem. For years he traveled up and down the river, surveyed, studying. Build a high dam in a deep canyon up stream to control the river he reasoned. In 1918 davis reported his findings and proposals to congress. Congress responded in 1928, passed the Boulder Canyon project act, authorizing construction of hoover dam to control and regulate the Colorado River. And the all American Canal system to deliver water to farmlands on the lower river. In 1930, president Herbert Hoover for whom the dam is named signed the appropriation bill to begin construction. Under a contract awarded in march 1931 to Six Companies incorporated a combine of six Major Construction firms, men and machines went to work to build this dam of unprecedented size. This modern Civil Engineering wonder, reclamation engineers rushed to completion specifications and design drawings. Crews at the dam site completed their surveys and investigations. The thunder of mans determination to conquer the colorado resevere berated between the sheer cliffs of black canyon as construction got under way. The first major task was to divert the river around the dam site. To do this four tunnels two on each side were drilled through the canyon walls. Each 56 feet in diameter they averaged 4,000 feet in length. Drill holes were packed with dynamite and blasted. Then trucks entered the tunnels and dumped the rocks. Workmen excavated over 1. 5 million of material from the four tunnels in 13 months. Tunnels then were lined with concrete three feet thick. Explosions rocked the canyon almost daily for almost two years before actual placement of concrete in the dam began. Acrobatic workmen called high scalers prepared the canyon walls for each blast. Suspend on ropes they drilled holes in the rock and loaded them with dynamite. After each explosion these daredevils swarmed over the cliffs, prying loose rock and clearing the walls of debris. In november 1932, the Colorado River was diverted. Under control for the first time in its history, the river flowed around and past the site. Men in trucks dumped earthen rock embankment across the canyon below the openings forcing the river from its age old bend through the huge diversion. A second earth and rock dam was thrown across the tunnel downstream keeping water from backing into the foundation area. Isolated and protected from the river by the two copper dams, the site was pumped dry. Men and machines dug 135 feet below the old river level to reach bedrock for the dams foundation exokay elevating over 2 million yards of rock and sand. As clean up of the dam site exposed the ancient bed of the Colorado River, geologists read the history of what happened ages ago. Workmen cleaned and prepared bedrock surfaces to receive the first concrete, assuring utmost stability for hoover dams foundation. 12 miles upstream, drag lines excavated sand and gravel for the dams concrete from an old stream bed deposit on the arizona side. A train hauled this raw material to an aggregate plant across the river a few miles above the dam site. Here the sand and gravel passed through various process of screening, grading and washing until it emerged as unexcelled aggregate. Then it was stock piled according to sizes to await its trip to the dam site. This process aggregate moved as called for in a steady flow over the railroad to two mixing plants one in the canyon bottom and the other on the nevada rim. There sand and gravel were blended with cement into a uniform mix, meeting rigid specific occasions for the 4. 5 million cubic yards of concrete to be placed in the dam structures. From the mixing plants, concrete was dispatched to all points of construction. Nine anchored aerial cable ways spanning the canyon from rim to rim lowered the concrete into the forms and handled other supplies and equipment as well. As the first bucket of concrete settled into its foundation on june 6th, 1933, hoover dam began its rise from the depts of black canyon. As concrete was dumped in the forms the dam reached its full 660 thickness at its base, poured in four foot layers of concrete, structures keyed or interlocking columns climbed sky ward as crews set new records daily. Bucket full after bucket full ran the continuous cycle, mixing plant from canyon rim out into midair from the george and down, dumping its load of 16 tons. Crews via bratd and compacted the fresh pours while buckets returned again and again to the mixing plants to be filled with more concrete or other waiting forms. Crews worked under all conditions, all seasons of the year without cessation, rain or shine, day or night. By june 1934 one year after the first pour, twothirds of the dams concrete had been placed in the forms. Hoover dam had risen to an impressive height already taking its place as one of the worlds wonders. As hoover dam climbed between its abutments, related structures also took form. At the toe of the dam the ushaped power plant to house generating equipment, control and maintenance facilities was built in twin wings, one along each side of the canyon walls. Intake towers, two on each side for the powered plant aspen stock system climbed as a maze of reinforcing steel and concrete, perched on shelves, these graceful columns rose 403 feet, well above the dams crest and the canyons rim. Two giant spillways were set against the canyon walls on each side of the reservoir just above the dam. These high Level Controls each capable of bypassing 200,000 cubic feast water per second assure that no water ill ever over top the dam. Water flowing into the basins plunges downward into the tunnels to enter the river below the dam, 100foot long drum gates rise during flood stage to give the reservoir an additional 16 feet of storage. Hoover dams pen stock system called for pipes of unprecedented size, ranging from 8 1 2 to 30 feet in diameter and 5 8 to 2 3 4 inches. Steel plate was brought from eastern rolling mills. A Steel Fabrication plant erected especially for this job near the dam site rolled and assembled nearly the three miles of pipe installed in the canyon wall tunnels. Hoover dams construction, fabrication of the pipe sections required special machinery and equipment. Edges of the dimension pilates were shaped on a plagt machine to assure precision and accuracy civilian later steps in the manufacture. Then they were bent on a giant press and rolled into circular form. One such plate equalled onethird of the complete s circumference of a pipe. Three formed a ring 30 feet in diameter and 11 feet long. Two of these rings joined, made up a section weighing 150 to 184 tons. A vertical lathe joined the edges. A train passing through one of the 30foot sections reveals their comparative size. When they were ready to receive the pen stock a specially designed trailer hauled them down to the dam site. At the can yom rim a 150 ton cable way relieved the trailer of its burdens, swung the pipe sections out over the gorge and lowered them under absolute control. Trailers waiting at portals of the access tunnels carried the home their permanent connections inside the main tunnels. The pipe sections were hoisted into location with cables, and joined end to end pressure pins to form continuous conduits between the intake towers, t turbines and outlet valves. A continuous stream of concrete had been pouring into the dam forms. The structure near its full height of 726 feet, far above the crest of any other dam yet built by man. On may 29th, 1935, two years after they had begun pouring, crews placed the last concrete in hoover dam. A total of 3 1 4 million cubic yards. This modern Civil Engineering wonder stood completed, 2 1 2 years ahead of schedule. On september 30th, 1935, president Franklin Delano roosevelt dedicated hoover dam to the nations progress. He praised its designers and builders. The dam stood like a sentinel white and beautiful in the desert sunlight guarding the river. Floodwaters lapped helplessly against its arched back as the reservoir filled. This manmade inland sea spread into the canyons and valleys. Hoover dam had conquered the colorado. Turbine fits to hold hoover dam seven big hydroelectric units were built into the mother house. Generator installations began in 1935. The first generator unit end two began commercial operation october 26th, 1936 to serve the stiff los angeles. Ones and, two the generators filled the pits as demand for Electrical Energy in california, nevada and arizona called them into service. Finally in 1959, manufacturing and installation of the last generator began. For 25 years it laid dormant and silent except for number of other hoover generators. Now as needed contracts were awarded for the generators manufacturer and installation. Plants throughout the nation fabricated the many parts. The design followed that of other hoover generating units. Its a 95,000 kilowatt, 60cycle, 16,500 volt generator. Falling water from the reservoir that spins and powers the 1a6 huge butterfly valve which permits the water to flow from the turbine weighing 2,000 tons the parts were shipped on 60 rail cars. The parts were lifted by cable way out over the canyon and down to the power house. Parts dissended into the gorge were familiar and almost daily sights. The main cable weigh operator was the same with one who helped install the cable way during the dams construction during the 1930s. Inside the nevada wing of the power house technicians assembled and installed the massive electrical cargo. Crews prepared the pit to receive the new generating unit. They removed temporary slabs over the relief valve outlets. Liners assembled in these opens were set in concrete. The turbine scroll case sections were lowered into the pit. Sections were levelled, bolted together and aligned. The completed scroll case was then anchored in concrete. Later the turbines water wheel attached to the bottom end of the shaft was installed inside the case. The butterfly valve was assem e assembled on the generator floor and later connected between the feeder pin stock and the turbine scroll case. Meanwhile the generators two main parts took form. Steel lamination plates were stacked around the row rotor frames. Coils were locked into place and connections were made. The power house lifted it from its erection bay and carried it gently to its foundation over the turbine bit where it was lowered and bolted into place. 466ton rotor was moved from its erection bay. Guide and thrust bearings and other parts were added to complete the assembly. After test runs n8 went on the line december 1st, 1961 to serve the state of nevada and complete the hoover power plant raising its capacity. Keeping it as one of the Worlds Largest hydroelectrical installations. Hoover dam had cost 175 million. Less than deferred payment of 25 million allocated for fund control. Hoover dams cost is being returned to the federal treasury at 3 interest from the sale of hydroelectric power. Its fulfilled the hopes of expectations of those who envision this great project. Colorado river waters that once destroyed man and his property now serve it. The colorado pours its waters into lake meade named for dr. Elwood meade. Lying calmly behind the dam they await