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OCH MOTTO:—“I* la Never Too Late to MendL” Established 188? Stfflwatar. Minnesota. TWs&y. Afcwl 29. 1920; ' " Voi. XXXIII: No. 39 „ The Construction and Operation of the Great Waterway Be tween the Atlantic and the Pacific J. Bernard Walker w Scientific American which for many cen- SsIS tur * es had possessed the minds of imm navigators, ship owners, captains of industry, admirals of fleets and governments of the world, was fulfiled when the Panama Canal was opened in 1914. Commenced by the French and completed by the United States Government, this great waterway between the Atlantic and the Pac ific, serving at once to sever two continents and unite two oceans, ranks, and will ever rank, as one of the greatest single engineer ing feats of all time. On May 4th, 1904, the'Government of the United States enter ed into possesion of a strip of land ten miles in width, extending across the Isthmus of Panama and from ocean to ocean, which is now known as the Canal Zone. On August 15th, 1914, a few days after the great war burst upon the startled world, the Panama Canal was opened to commerce. The. Isthmus of Panama, a narrow neck of land, about thirty miles wide as the crow flies, connects the two continents through an elbow which is in the form of a segment of an arc, and runs approximately east and west, the Canal extending across the Isthmus in an approximate north and south line. In places the land is gently undulating, in others, more hilly and picturesque, and at the great Gail lard Cut, formerly known as Culebra Cut, it passes through the Continental Divide, which here rises some 700 feet above sea level. The route follows the valley of the Mindi and Chagres Rivers on the Atlantic slope of the Divide, beyond which it passes through the valley of the Rio Grahde on the Pacific slope down to tidewater. Sea level channels were dredged inward from either end of the Canal as far as practical, that is, from deep water in the Atlantic southward to Gatun, and from deep water in the Pacific northward to Miraflores. The intervening distance from Gatun to Miraflores consists of two artificial lakes which were formed by damming the waters of the Chagres and the Rio Grande Rivers. The first of these, Gatun Lake, extends from Gatun to Pedro Miguel on the Pacific side of Gaillard Cut. Then folows Miraflores Lake, which extends from Pedro Miguel to Miraflores. The ele vation of Gatun Lake is 85 feet above sea level, and of Miraflores Lake 54 2-3 feet above sea level. In making a trip through the Canal, let us say from the Atlantic to the Pacific, the first evidence of this vast work will be a view of the great rock breakwater, which has been built out from .Toro Point into Limon Bay, or Colon Harbor, for a distance of over two miles. The purpose of this breakwater is to convert the bay into a safe anchorage, to pro tect shipping in the Harbor of Colon, and to shelter vessels which are making the Canal. To the left, extending from Cristobal, is a great artificial mole, from which six fine piers reach into the bay. Beyond the end of the lighthouse commences a channel with a depth of 45 feet and a width of 500 feet which extends in an almost straight line for seven and one-half miles to the Gatun locks. The locks are on the left side of the Chagres valley, and to the right of them the valley has been closed by a huge"dam one and one half miles in length, nearly half a mile wide at the widest point of its base, and about 100 feet wide at the top. This dam cuts squarely across the bed of the old Chagres River and serves to impound its waters, forming a lake whose area is 164 square miles and whose normal elevation is 85 feet above sea level. During the rainy season, floods of great volume pour down the Chagres River into the lake, and the surplus waters are allowed to flow over a concrete spillway, the discharge channel of which is 285 feet wide and 1,200 feet long. The spillway dam is in the form of an arc of a circle, and measures 808 feet along its course. The top of the dam is 69 feet above sea level, and it is surmounted by regulating gates 20 feet high, the tops of which are two feet above the maximum elevation of the lake. The height of water in the lake is controlled by these gates, which slide be tween vertical concrete piers. They are raised and lowered by electric power from a power plant at the spillway, which serves also to provide power for the electric opera THE PANAMA CANAL TODAY tion and lighting of the locks and the gen eral plant throughout the full length of the Canal, which, it should be said, extends for a total distance, from deep water to deep water, of about 49 miles. The Gatun dam consists of two mas sive rock fills, with a vast central core of mud and clay which was pumped in hydrau lically and allowed to settle and solidify. It has proved to be perfectly watertight, thus allaying the many fears which were expressed as to the possibility of damming the Chagres River and holding back an artificial lake of the great size of Gatun. The difference of elevation of 85 feet between sea level and Gatun Lake is overcome by a flight of three pairs of locks. Each lock is a thousand feet in length and 110 feet fn width. When the ship comes to rest alongside of the central pier, which is a 1,000-foot extension of the middle wall of the locks, it is taken in charge by electric towing locomotives, two or three on each side, according to the size of the ves sel. The ship is not allowed to use its own power, but is towed into the locks and taken from lock to lock by the electric towing lo comotives. On emerging from the upper lock, the ship passes into Gatun Lake and proceeds under its own power at speeds of from ten to fifteen knots, according to the depth of the channel which is being dredged in the bottom of the Lake. The ship steams' through the Lake for 24 miles until it reaches the Continental Divide above re ferred to. Here the hills begin to close in on the channel, and for the next eight miles or so, it passes through a deep cut through the mountains. Here the channel is 300 feet wide at water level, and at one point, Gold Hill, the sides of the cutting rise about 500 feet above the bottom of the Canal. Emerg ing from the Gaillard Cut, the ship arrives at the locks on the Pacific side known as Pedro Miguel. Here in a single flight the ship is lowered from the elevation of 85 feet of Gatun Lake, to Miraflores locks, where in two flights it is lowered to sea level. From Miraflores locks, it passes trough a dredged channel some 8 miles in length, at the end of which it finds itself in deep water. The two controlling problems, from the engineering standpoint, in building the Canal were the construction of the Gatun dam, locks and spillway, and the great cutting through the mountains in Culebra. In both cases the task was complicated by very poor quality of the material in and on which these great works had to be carried out. The ground at Gatun was of a loose and more or-less swampy character, and the rock is of a late geological formation, which, when ex posed to the air and to the heavy rains of the rainy season, rapidly loses its consistency. Fortunately, a fair quality of rock was found at the base of the hills on the easterly side of the site of Gatun dam, and through this the great flight of locks was built. Toward the center of the axis of the dam was an other slight hill of rock which was selected for building the spillway. The stability and water tightness of the dam is secured by its enormous width of half a mile and the vast core of impervious clay slit which forms its center. The cutting at Culebra was the other great obstacle, and here the problem was one of disposal of the spoil or material. The rapidity with which these enormous masses of material were execavated and taken away was due to the use of the very best American execavating machinery, coupled with a skillfully laid out plan of railway trackage. When the United States purchased the Canal from the French company they found that over 78,000,000 cubic yards had been taken out; but of this only about 30,- 000,000 was useful to the enlarged American canal. The total excavation, dry and wet, for the Canal as originally planned, was estimated at about 104,000,000 cubic yards, in addition to the French excavation. Ad ditions brought the estimated total to 182,- 500,000 cubic yards. The great slides which more than once entirely filled the Canal were due to the fact that whereas the cross section of the Canal, as planned, called for side slopes to 1, it was found that the rock around Cucaracha, and particularly at Culebra, was of such un , 3'" stable quality that it was not able to sustain its superincumbent pressure where the depth of the cutting ran into the hundreds of feet. Ultimately it became evident engi neers that nature must be alloweato have its way and to assume a slope agreeable to the nature of the material. Consequently, a great force of dredges was set to work tak ing out the material of the slides as it flowed into the Canal. The work was carried on steadily and on a great scale, until at last the slides came to rest at an inclination of one to seven. It is gratifying to learn from the last report of the Governor of the Panama Canal that from the standpoint of engineering and maintenance, the Canal is functioning ad mirably. Of the total rainfall of the Gatun Lake watershed, 12 per cent was absorbed by evaporation, 20 per cent by the hydraulic electric plant at Gatun, 9 per cent by lock ages and miscellaneous uses, leaving a mar gin of 59 per cent which passed over the necessary spillway discharge to maintain the lake at the standard level during the wet sea son. On December 15, 1918, the elevation of Gatun Lake was 86.98 feet above sea level, and on April 12, 1919, it had been re duced to 83.73 feet. The maximum current velocity, as recorded in the Gaillard Cut section of the Canal was 0.94 knot per hour, which occurred opposite Gold Hill, eight minutes after both chambers of the Pedro Miguel locks had been filled simultaneously. The number of lockages during the year for all three series of locks was 6,938. Two thousand and sixty-one commercial ves sels passed through the Gatun locks, and 282 vessels of the United States Army and Navy for which no tolls were paid. The average time of transit through the Canal was about ten hours. A new generator unit No. 4 at the Gatun hydraulic-electric section was placed in operation last year bringing the capacity up to 13,500 kilowatts. An additional unit No. 5 has been ordered. The great Cucai acua slide, from which a total of 5,063,852 cubic yards has been removed by dredges, has been quiescent through the year, and the Culebra slides on the northern side of the Divide have been fairly quiescent. There has been removed from the Culebra slides to date by dredges the vast total of 25,000,000 cubic yards of material. Hydraulic work is being done in sluicing down and reducing the weight of the banks where slides have occurred. On June 30, 1919, 3,454,800 cubic yards re mained to be removed from the Canal prism, practically all of it being chargeable to main tenance. At no time during the year was there difficulty in maintaining the full width and depth of the channel in the Culebra slides region. • On June 30, 1919, the total force em ployed by the Panama Canal and the Pana ma Railway Company on the Isthmus was" 20,361. The total number of ships making the transit of the Canal during 1919 was 2,025, of which 860 passed from the Atlantic to the Pacific and 1,1165 in the contrary direction. The aggregate net tonnage was 6,131,575 tons. The average net tonnage of commer cial ships passing through the Canal was 3,337 tons. The ships entering the Canal were classified as follows: United States, 786; British, 672; Norwegian, 128; French, 104; Chilean, 83; Japanese, 87; Danish, 79; and the ships of other nationalities in de creasing numbers. The time saved these vessels ran in individual cases as high as 45 days. One vessel from Galveston for Yoko hama saved more than $5,000 on the out ward voyage alone, as compared with the cost via the Suez route. The tolls collected from vessels using the canal during the year amounted to $6,139,599. The report of the Governor for 1919 tells us that the ordinary expenses for opera tion and maintenance of the Canal, includ- ing those fif civil government and sanitation, amounted t0*56,112,195. Offsetting the ex penses of operation and maintenance is the amount earned as tolls for vessels passing through the Canal as given above. The total revenues derived from busi ness operation carried on with Panama Canal funds amounted to $13,684,881, an increase of 32 J 4 per cent over 1918 and 45 per cent over 1917. The cost of carrying on these operations during the last fiscal year amounted to $13,623,854, leaving a net pro fit of $61,027. SOIL DRAINAGE . \ Reclamation of the Swamp Lands for Fanning Possible, in Unsettled Parts of Our State Paper Bead Before Pierian Chautauqua Orel* m Behalf of date A, bp I. C, B. paSpjjlHE TIDE of emigration which caused most of our fore-fathers westward and north-westward in search of agricultural lands took no note of the vast agricultural possibilities of northern Minnesota, Wisconsin and Mich igan. One reason for this is that these sec tions were heavily forested and that they presented some peculiar difficulties which caused the pioneer farmer to be rather dif fident about attacking them. The fact re mains that the cut over lands of these three states with'excellent soil and climatic condi tions for many farm crops and for stock raising, remain as yet comparatively unset tled and open for development. Let us dis cuss one of the difficulties, which with proper state aid can easily be overcome, that is hold ing back farming in northern Minnesota, namely soil drainage. We are accustomed to think of soil as just dirt, but when we study it carefully we find that it is one of nature’s most complex laboratories, teeming with microscopic plant and animal life. A normally fertile soil is composed of fine parts, mineral matter, which is really finely divided rock particles worn small by the different agencies of wea thering; organic matter, which is composed of decayed and decaying plants and animals; soil air; soil water; and soil bacteria, which are the microscopic plants which bring about chemical changes in the soil and render the plant food soluble and available for the use of the plants. For a soil to be productive all of these constituents must be present in some degree. This brings us to the subject of drain age and why it is necessary. All soil to be productive must be drained of its surplus water. Sometimes this is done by Nature where the surplus water in the surface soil is drained off by underground movements so that plants can thrive. But \vhere this is not done we naturally must do it artificially. We will try to give you briefly the reasons this is necessary. In the first place the soil water, which envelopes each soil particle with a tiny film of water and keeps the soil moist, should not be confused with the surplus water. The latter is carried in the spaces between the soil particles and hence is of no use to the growing plant. It occupies the space in the soil which should be occupied by soil air and thus prevents the soil from being pro perly ventilated. A wet soil is always a cold soil and therefore is the last to warm up in the spring and the first to feel frost in the fall. I have found; by actual experiment, 12 de grees difference in the temperature six in ches below the surface, in drained and un drained soil in the same field in the month of September. The surplus water in soil prevents the growth and activity of the soil bacteria which are necessary to bring about chemical changes and for the decay of vegetable mat ter such as roots, stems and leaves of plants which are plowed under, or the barn yard manure which has been spread upon the field and plowed under. These bacteria also develop and multi ply much more rapidly in a warm than in a coxd soil, which gives us another argument in favor of drainage. Many of you are doubtless familiar with the immense peat beds and muskeg swamps so plentiful in this state. These are formed solely because they are too wet to decay and they never will de cay until they are underdrained so that the decay bacteria can work. The draining of low and wet spots in the land allows the farmer to make his fields more uniform and regular in shape and size, thus enabling him to do his work more economically. All of the farm can be worked instead of only the high spots and the farm will not be cut up by strips of wet land which can not be cultivated. Land that is thoroughly drained can be worked much earlier in the spring, as it drys out quicker and gets in a good physical con dition earlier. This enables the farmer to get his crops in earlier and lengthens the growing season which is a very important item in Minnesota. This last point we wish to make in favor of drainage is- that it renders the lo cality much healthier for man and beast. The damp air of the swamps is replaced by the air purified by the growing crops. The breeding plslce of mosquitos and other in sects is destroyed and the whole climate is warmed up and made healthier. Now that we have tried to show you why soil drainage is necessary, we shall try to show you briefly how to drain. Broadly speaking there are two methods of drainage, surface drainage and under drainage. Surface drainage is accomplished by open ditches dug through the land to be drained and emptying into a large ditch or nearby stream, if one is available. This method is generally the one first employed and is quicker and cheaper in first cost than any other method. In many of our peat and muskeg swamps, large dredge ditches have been constructed by the State or county, for a distance of from ten to fifty miles, through the country that needs draining Then the farmer, or in many cases the town ships, along this ditch run in subsidary ditches with laterals running from these. In this way the peat and muskeg is given a chance to decay and settle before installing a permanent system of underdrainage. The objections to the open ditch method of drainage are many. In the first place it cuts the farm and fields up so that there is lots of turning and working small corners. It is a temporary affair, as a ditch begins to fill up after the first year and must be cleaned often thus renewing the cost every few years, and last, it gives noxious weeds and destructive insects a haven along its sides from which they keep spreading to the adjoining fields increasing the expense of raising a crop. The best and most satisfactory method of drainage land is the second method, or un der-drainage. By /this method an under ground passageway is provided at regular intervals by which the water can find its way to a lower level either into a large ditch, convenient stream or a ravine. There are many make shift ways of providing this pas sageway but the best and most permanent method is by tiling. Drain tile are hollow, unglazed clay cylinders, varying from four inches to thirty six inches in diameter, which are laid end to end in the bottom of a ditch with just enough fall to carry the water in the desired direction. The joints are not fitted closely, but allow water to enter, while they are tight enough to keep the dirt out. A fall of one inch to a hundred feet is enough to carry off the water and they are generally laid from thirty to forty inches be low the surface. In very wet land five or six inch tile ditches, fifty feet apart, will drain the land perfectly. The advantage of this method is that it is permanent and that you can work every foot of the land right over your tile which is always on the job. After a couple of years the soil seems to get honeycombed with minute passageways so that the water is removed right after a rain and the land can be worked within a few hours. In sections where tile are not available or the farmer can not afford so heavy an in vestment, poles, stones or plank may be used to take their place. We have seen some very successful draining done on a small scale by laying three tamarack poles in the bottom of a ditch then throwing in a little hay or straw, to prevent the dirt working between them, then fulling the ditch with dirt. Drainage was invented in Scotland, where they built underground drains from flat stones, and many are in perfect working order which were built more than a hundred years ago. We would like to leave this thought with you. If a small fraction of the money spent by the government in the reclamation of a like area of arid and semi-arid lands of the West were spent on the swamp lands of northern Minnesota, some of the finest farm lands in the United States could be made available for settlers in one of the finest cli nates and best States on the continent. George Cohan, the composer of, “Over There” received $25,000 as soon as die song was finished besides large royalties afterward.