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noted in the previous annual report, it was decided to install 500-kilowatt power transformers and the necessary equipment for

transmission line an overhead system of 44,000 volts, extend stepping the 44,000 volt transmission line pressure down to 2,200 m Balboa to Cristobal, and connecting the existing Miraflores volts. power station with the Gatun hydroelectric station, so that High-power transmission line.-Under a contract dated March 31, ay be operated separately or in parallel as necessary. Four 1913, 794 double-track span bridges and 20 single-track span bridges ions are provided, located at Cristobal, Gatun, Miraflores, and were to be delivered on the Isthmus. These have all been erected in · The excavation for the Gatun substation was begun ou place with the exception of five special towers which will be required Der 26, 1913, and the steelwork, furnished and erected under at the Cristobal and Balboa terminals, and one bridge at Cristobal. E, was completed on February 19, 1914. The installation of Under contract there have been purchased and received to date for trical equipment of the building has been governed by the the transmission line 1,562,208 feet of 2/0 Brown & Sharpe gauge s made in building construction and at the close of the year stranded copper and 512,065 feet of five-sixteenths inch copper-clad ber cent completed. The total amount thus far expended on wire. At the close of the fiscal year 1,408,443 feet of 2/0 conductor ding is $145,717.92 and on the installation of the machinery cable were erected. The total amount expended on the transmission 11. The Cristobal substation was installed for the purpose line was $1,014,383.29, of which $701,222.62 were covered by conshing power required by the coal-handling plant, the Mount tracts and the balance expended on inspection and installation. imping plant, and the miscellaneous requirements in the Cables.—The total amount of cable on order, received and installed of Cristobal. Excavation for this structure was begun on up to the end of the fiscal year was 2,659,403 feet, of which 1,531,528

1914, and the erection of the steelwork under contract was feet is lead sheathed and 1,127,875 feet is rubber covered, doubled on May 6, 1914. The amount expended on the building braid wire and cable. At the close of the fiscal year 1,462,684 feet ion was $111,858.01 and on the electrical installation of lead-covered cable had been pulled into the ducts and 911,816

The Miraflores substation is being installed for the pur- feet of rubber covered had been used for the conductor slot feeds, aring for the power requirements of Miraflores and Pedro

control connections, etc. ocks, and also for the purpose of serving as a step up trans Telephone system. -An elaborate system of telephone communicaation for Miraflores steam plant. The foundation work was tion has been designed for the operation of the locks and a contract d on October 29, 1913, and the steelwork under contract awarded for the complete equipment. It is to consist of three subMarch 9, 1914. The electrical equipment is 22 per cent divisions: First, that required for the control of vessels passing

The amount expended thus far is $155,532.20, of which through the locks; second, that required in the upkeep and main4 were for building construction and $52,023.16 for eler tenance work in the lock tunnels; and third, that required for local allation. The Balboa substation was located for the pur public service. The total amount of the contract is $6,949.35. pplying power to Balboa shops, the air-compressor plant.

Emergency dams.—The emergency dams at Gatun were completed pumping plant, coal-handling plant, and Ancon pumping before the close of the last fiscal year, but the final acceptance tests had well as other local purposes. Work was begun on this sub- not been finished. During the year the two dams at Gatun were acApril 27, 1914, and the steelwork erected under contract cepted and the dams at Pedro Miguel and Miraflores were finished and eted on June 27, 1914. Four per cent of the electrica accepted, the first at Pedro Miguel on September 16, 1913, and the was installed. The total amount expended thus far is

second on October 17, 1913; at Miraflores the first was completed of which $45,565.12 were for building construction and and accepted January 14, 1914, and the second on February 7, 1914. or electrical installation. In order to supply power to the

A test was made at Gatun in May, 1914; the dam was swung, girders e of the Darien wireless station, being constructed by the

and gates lowered, and the pipes driven to close the spaces between brities for the Navy Department, arrangements have been

the ends of the gates. The upper lock was then filled with water stall a small substation of 400-kilowatt capacity, tapping

to lake level, the upper guard gates and upper operating gates were ission line and stepping the voltage down to 440 volts

opened, and the intermediate and lower gates of the lock closed. the location of the pumping plant from Miraflores to

The upper lock was emptied through the culverts until the water s necessitated the installation of a substation at this locs

level was below the guard-gate sill. This brought the full head of der to supply the necessary power in connection with the

473 feet on the emergency dam, which was found to have a leakage ant, arrangements were made for the installation of two

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of 950 cubic feet per second. This leakage produced no dangerous current in the lock, and it would have been easy to close any of the lower gates in the face of the stream. Another purpose of the test was to determine whether the emergency dam could be used in lieu of a caisson for unwatering the locks so as to permit access to the gates for painting, but the leakage was too great to use the dam, as it at present stands, in lieu of the caisson. Experiments are being made to devise a means of stopping the flow. The total amount expended for the emergency dams was $2,206,984.67, of which $1,958,329.90 were covered by the contract for delivery of the material and its erection, and $248,654.73 for inspection and other expenses assumed by The Panama Canal under the contract.

Floating caissons.A description of the caissons for closing the entrance to the locks, including the pumping plant for unwatering the lock chambers, was given in the last annual report. Bids were invited on May 21, 1913, for furnishing the material, constructing and delivering the caisson on the Isthmus, and there were two bidders, the lowest bidder offering to construct the two caissons and deliver them at Balboa for the sum of $648,300, and the price for one was given at $330,760. A contract was entered into for one caisson under date of August 22, 1913.

Pontoon bridge.-In order to maintain communication across the canal with the west side, it was finally decided to construct a pontoon bridge at Paraiso for carrying the Panama Railroad. This bridge was constructed at the expense of the Panama Railroad Co., but the design and construction were undertaken by Commission forces. The approaches and abutments were built under the direction of Mr. A. S. Zinn, resident engineer; the pontoon and superstructure by the dredging division under Mr. W. G. Comber; the track work by the Panama Railroad Co., and the operating machinery by the first division of the chief engineer's office. The bridge revolves about a pivot at one point, similar to pontoon bridges successfully operated for many years on the upper Mississippi, plans for which were furnished through the courtesy of Mr. C. F. Loweth, chief engineer of the Chicago, Milwaukee & St. Paul Railway Co. The pontoon is 378 feet long over all, 55 feet wide, and 6 feet 3 inches deep at the center line. The base of the rail is 33 feet above the bottom of the barge, or 30 feet above the water level. The apron girders are 64 feet long, resting on hinged supports at both ends, and consist of spare lock gate parts. Arrangement is made at each end of the girder for automatically providing for a variation of 6 feet in the water level of the canal. When the bridge is turned the girders are lifted clear of the concrete piers by an electrically driven mechanism and temporarily supported by blocking on the ends of the barge. The bridge is revolved by means of a 1-inch anchor chain fastened at each bank, which passes

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cubic feet per second. This leakage produced no dangerous around an electrically driven wildcat on the deck of the pontoon,

in the lock, and it would have been easy to close any of ty near the west end. The mechanism for lifting the apron girders and gates in the face of the stream. Another purpose of the tes

for turning the bridge, and also for operating the rail lift, the rail determine whether the emergency dam could be used in li latches, and the main latch at the west pier, is operated from a cenisson for unwatering the locks so as to permit access to the

tral panel. The total cost of the bridge to June 30, 1914, was or painting, but the leakage was too great to use the dar

$218,331.78. present stands, in lieu of the caisson. Experiments are beir

Operation of locks.-The lockages made during the fiscal year gave devise a means of stopping the flow. The total amount er:

an opportunity to try out the locks and their machinery. The first for the emergency dams was $2,206,984.67, of which $1,65

one at Gatun was made on September 26, 1913, when the tug Gatun were covered by the contract for delivery of the material al

was put through the Gatun Locks, followed on October 14, 1913, when ction, and $248,654.73 for inspection and other expenses

a part of the dredging equipment was locked through the Pacific by The Panama Canal under the contract.

locks to the lake level. From these dates throughout the year various Fing caissons.--A description of the caissons for closing t.

craft belonging to The Panama Canal were passed back and forth e to the locks, including the pumping plant for unwatering

as the necessities of the work required, in addition to the tows that < chambers, was given in the last annual report. Bids wet

were instituted for handling freight from the Balboa terminals to on May 21, 1913, for furnishing the material, constructir

Colon and Cristobal for the Panama Railroad Co. To try out the ivering the caisson on the Isthmus, and there were two bi

towing locomotives, the Panama Railroad steamers Allianca and Le lowest bidder offering to construct the two caissons and d

Ancon were locked through Gatun Locks and returned, and through em at Balboa for the sum of $648,300, and the price for cu

the courtesy of the agent of W. R. Grace & Co. the Santa Clara was en at $330,760. A contract was entered into for one cais

locked through the Pacific Locks and returned. late of August 22, 1913.

The operation of the locks has developed certain facts in regard pon bridge.-In order to maintain communication across t

to the action of flowing water which had not been anticipated. As ith the west side, it was finally decided to construct a ponto previously noted, the gates of the upper locks of each flight and of at Paraiso for carrying the Panama Railroad. This bride the Pedro Miguel Locks are duplicated. The upper pair of gates is estructed at the expense of the Panama Railroad Co., but the called the guard gates and the lower pair of the upper two the lock ind construction were undertaken by Commission forces. 1

gates. At the lower end of the locks the upper pair of gates is called hes and abutments were built under the direction of Mr. A.

the safety gates and the lower pair of the two the lock gates. The esident engineer; the pontoon and superstructure by space between the guard gates and the lock gates is regulated by an g division under Mr. W. G. Comber; the track work by to

auxiliary culvert, while the space between the safety gates and the Railroad Co., and the operating machinery by the first dir lower gates is regulated by a T culvert. When the water in the che chief engineer's office. The bridge revolves about a pin upper lock is low and the valves are open there is a sudden drop of point, similar to pontoon bridges successfully operated the water level in the forebay. This is more noticeable at Pedro cars on the upper Mississippi, plans for which were furnishe Miguel

, where the canal above the forebay is relatively narrow, than the courtesy of Mr. C. F. Loweth, chief engineer of v it is at Gatun and Miraflores, where the forebay opens immediately , Milwaukee & St. Paul Railway Co. The pontoon is 378 din into the lake. This

drop is faster than can be followed by the water r all, 55 feet wide, and 6 feet 3 inches deep at the center Li in the space between the guard and upper gates, and the result is a of the rail is 33 feet above the bottom of the barge, or 30 fe reverse head on the guard gates, causing them to open at the miter. e water level. The apron girders are 64 feet long, rest

This reverse head lasts but a short time. d supports at both ends, and consist of spare lock gate pare

In the first lockages the T culvert regulating the space between ment is made at each end of the girder for automatica.

the lower and safety gates was in free communication with the side g for a variation of 6 feet in the water level of the case

wall culvert near its lower end, but above the lower valves. When e bridge is turned the girders are lifted clear of the concre

the upper valves were raised the water in the space between these an electrically driven mechanism and temporarily supporta

gates rose faster than in the lock; consequently there was a reverse ing on the ends of the barge. The bridge is revolved

pressure on the safety gates, causing them to open at the miter, the a 1-inch anchor chain fastened at each bank, which para

pressure being sufficiently great to compress fully the springs in the

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gate-maneuvering struts. Due to the possible danger of crippling the moving apparatus by such reverse stress, the valves in the T culvert were partially closed, choking the communication between the side-wall culvert and the space between the gates. By experimenting, a degree of closure was reached which caused the water in the space between the culverts to lag behind the water in the lock when filling, and at the same time to fall rather more rapidly when emptying. In this way a positive pressure was always kept against the safety gates. With the use of both side and center wall cul. verts, as the rapidity with which the water level in the lock changes is greatly increased, a different adjustment will be necessary.

When the valves in the side culvert are raised and the water enters the lock the flow of water is greater through those openings in the laterals which are nearest the middle wall than through those nearer the side culvert. As the water rises in greatest volume next to the middle wall, there results a slight slope of the surface toward the side wall. When both side and middle culverts are used no such action is noticeable. The first gush of water from the side culverts appears to come from the highest laterals and then successively from the others. So far as can be ascertained, however, it can not be stated that the discharge is greatest from any one of the laterals.

In filling or emptying a small canal lock the water levels approach each other with a rapidity depending upon the square root of the diminishing head. Toward the end of the operation the change in level becomes slower, and the flow of water is supposed to cease either just before or at the equalization of the levels. Frequently the gates are opened with a very slight head against them to avoid the loss of time involved in waiting for the head to vanish entirely. In filling or emptying the locks of The Panama Canal there is a noticeable overtravel of the water, so that the water in the chamber which is filled rises slightly higher than the level in the chamber from which the water is drawn, and the gates separating the chambers become subjected to a reverse head. At Pedro Miguel it is noticed that the water rises from 0.3 to 0.6 of a foot higher than the water in the forebay, tending to throw the upper gates open. difference in head is of short duration, but is very noticeable, and is taken as an indication of the instant when the apparatus for opening the gates should be put in motion. This acts as a safety device to the motors which operate the gates.

In the annual report of the Isthmian Canal Commission for 1911 is described the method used for overcoming differences in pressure on the lower gates at the lower lock at Miraflores and Gatun, due to the difference in density of the water above and below the gates, in consequence of which the culverts were turned up at the outer end so as to reduce the pressure to a manageable quantity. It is possible

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euvering struts. Due to the possible danger of cripplin that the overtravel of the water from the emptying lock into the tail ing apparatus by such reverse stress, the valves in the 1

bay may result in continuing the flow of the fresh water through the were partially closed, choking the communication betwee

culvert beyond the point at which in theory it should cease and, wall culvert and the space between the gates. By exper: therefore, in obviating the danger of the resultant pressure. Howa degree of closure was reached which caused the water i

ever, no trouble is experienced from the resulting pressure against e between the culverts to lag behind the water in the lower

the lower gates. The difference in density of the water above and ing, and at the same time to fall rather more rapidly whe

below the gates is, however, noticeable in another way. When the In this way a positive pressure was always kept agains

lower gates are opened the fresh water rushes out with considerable y gates. With the use of both side and center wall cu

velocity on the surface of the salt water below, and there is a correthe rapidity with which the water level in the lock change

sponding rush of salt water along the lower strata. This current increased, a different adjustment will be necessary. continues for a considerable time and has a noticeable effect on veshe valves in the side culvert are raised and the water enter

sels leaving the lock, sheering them away from the middle wall as the flow of water is greater through those openings in to

soon as they pass the angle of the side wall. thich are nearest the middle wall than through those neare

The slope given to the water in the lock by use of the side culverts culvert. As the water rises in greatest volume next to the has already been noted. The same effect was noted during the filling all, there results a slight slope of the surface toward tim of the lowest lock with fresh water when the lower gates have been · When both side and middle culverts are used no such a

left

open long enough to insure salt water filling the lock. The slope oticeable. The first gush of water from the side culvert is from the middle wall so that the ship moves to the side wall and o come from the highest laterals and then successively free

the towing locomotives are unable to hold a large vessel central in 3. So far as can be ascertained, however, it can not be state

the lower lock during the entire process of filling when the side lischarge is greatest from any one of the laterals.

culvert only is used. ig or emptying a small canal lock the water levels approe.

As noted in previous annual reports, in the formula for filling and er with a rapidity depending upon the square root of t

emptying the locks the coefficient of flow C, used to determine the ng head. Toward the end of the operation the change real velocity, was assumed at 0.65, this being slightly more favorable omes slower, and the flow of water is supposed to create than experience at other locks has shown to be readily obtainable, st before or at the equalization of the levels. Frequent

but the nature of design and construction warranted the assumption. are opened with a very slight head against them to arou From experiments made at Pedro Miguel when the lake level was at f time involved in waiting for the head to vanish entire reference 84.8 and the water in the lock was at reference 50.9, the or emptying the locks of The Panama Canal there is

value of C for the side culvert, with both valves open, was determined overtravel of the water, so that the water in the chambe

to be 0.886, much more favorable than was anticipated. Similar obfilled rises slightly higher than the level in the chama

servations, using only one valve, were made both at Pedro Miguel eh the water is drawn, and the gates separating the che and in the upper lock at Gatun 'as a check, and the value of C was me subjected to a reverse head. At Pedro Miguel it

found to be 1.177 and 1.272 at the two locations, respectively. The at the water rises from 0.3 to 0.6 of a foot higher than to

value of the coefficient for emptying the lock at Pedro Miguel is he forebay, tending to throw the upper gates open. somewhat less favorable than that for filling, the coefficient C for In head is of short duration, but is very noticeable, and

the side culvert being found to be 0.804 when both valves were used. indication of the instant when the apparatus for opening

At Gatun and Miraflores, where the culvert is turned up at the Chould be put in motion. This acts as a safety device 11

discharge, the coefficient of flow for emptying the lower lock is which operate the gates.

about 8 per cent less than through the level discharge at Pedro nnual report of the Isthmian Canal Commission for 24

Miguel. When the middle wall culvert is used in combination with the method used for overcoming differences in presse

the side culvert the time of operation is greatly reduced. The Pedro er gates at the lower lock at Miraflores and Gatun, dues

Miguel Lock can be filled or emptied in about eight minutes without ace in density of the water above and below the gates

causing too great a disturbance in the chamber. Observations have e of which the culverts were turned up at the outer el

not yet been made with the middle culverts at Gatun and Miraflores. Luce the pressure to a manageable quantity. It is possibi

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