944 THE PANAMA CANAL AND CANAL ZONE 



in San Francisco is to be held in 1915, it seems certain that vessels may use the canal 

 in the latter part of 1913. Some excavation will be done by dredges after the waters 

 are let in. By estimates made late in 1912: in the Atlantic division, the concrete work 

 at the N. end of the locks should be finished June 30 and the Gatun spillway on August 

 i ; in the Pacific division, the Miraflores spillway on June 30; and in the Central division 

 the Culebra cut about July i but this depends partly on slides such as occurred during 

 the last year and delayed progress somewhat. 



On October i, 1912 the remaining excavation was estimated at 31,803,126 cu. yds., 

 of which about one half had been added to the estimate during 1911-12. Of this 

 additional amount, which is nearly 8% of the grand total of 212,227,000 cu. yds., 1 

 nearly 12,000,000 cu. yds. was in the Pacific division, including 8,794,000 cu. yds. for 

 dry-docks, coaling station and terminal at Balboa; only 4,615,000 cu. yds. was in the 

 Central division, because of slides and for changes in the Obispo diversion; and 295,000 

 cu. yds. in the Atlantic division, largely for silting in the finished channel. The total 

 excavation for the fiscal year (July i, 1911 to June 30, 1912) was 30,302,261 cu. yds. 

 nearly 2,000,000 cu. yds. less than in the preceding year and less than in 1910 or 1909. 



Apart from slides, the Central division and particularly the Culebra cut therein is 

 the most difficult part of the canal. On November i it was estimated that the cut 

 was 93.19% completed. The seriousness of slides in this part of the work has at times 

 been exaggerated. The slides are largely due to abrupt transitions from one geological 

 formation to another. The> have occurred usually in dry seasons. Although there 

 is sometimes no danger where the slope is i on 5 or less, there have been slides when 

 the inclination was i on 7 or more. The commission's geologist says that, where there 

 are strong lavas, walls may safely be nearly perpendicular but that there will have to be 

 a slope of i on 5 for soft rocks and i on 10 in much sheered soft clay; and that there will 

 be no more danger than in a naturally formed valley when the surface is protected by 

 vegetation which covers the sides of the cut very rapidly. A slide on the W. bank at 

 Culebra covered 63 acres in 1912 and one on the E. side about 50.7 acres. During the 

 last fiscal year (ending June 30, 1912), three steam shovels were terracing either side 

 of the cut. Slides at Culebra do not mean an increase of cost over the original estimate, 

 because the cost of excavation and of spoil-disposal has been decreased: the former 

 from 11.5 to 8.88c per cu. yd., and the latter from 18.54 to I5-22C per cu. yd., although 

 the distance over which waste must be carried has been made nearly one half greater. 



On October 19, 1912 93% of all concrete for locks was in place, the remainder being 

 296,672 cu. yds. in a total of 4,352,563; more than 92% of the concrete for the double 

 three-step locks at Gatun 2 ( Atlantic side), the remainder being 149,670 cu. yds. in a 

 total of 2,050,000; more than 91% of the spillway for the Gatun dam (to discharge 

 137,000 cu. ft. a second, thus caring for the Chagres' floods), the remainder being 

 18^185 cu. yds. out of 225,000; about 93% of the Gatun Dam (115 ft. high, covering 

 400 acres and impounding 164 sq. m. of water) which held without leakage 57 ft. (maxi- 

 mum height estimated 87 ft.) of the waters of Gatun Lake at the end of the rainy 

 season; and, nearer the Pacific entrance, more than 99% of the double one-step Pedro 

 Miguel lock, the remainder being only 7,048 cu. yds. out of 889,827, and more than 90% 

 of the double two-step lock at Miraflores, the remainder being 139,914 cu. yds. out of 

 1,412,736. 



The installation of lock machinery began at Gatun in September 1911 and at Pedro 

 Miguel in January 1912. A bull-wheel for turning lock gates is one of the valuable 

 inventions 3 that have grown out of actual work on the canal. All locks are in pairs 



and Karl Bitter "director of sculpture." The exposition has a base fund of $17,500,000, 

 $7,500,000 subscribed by citizens of San Francisco and vicinity, and $5,000,000 in bonds from 

 the state and the city each. 



1 Of this total only 29,9o8,ooo"cu. yds. is usable excavation by the French. 



2 The channel between Gatun locks and the Atlantic was completed on February 24, 1912, 

 through the Mindhi Hills, except a dike separating the cut from the French canal. 



3 Others are a machine for shifting railway tracks used in carrying away spoil, and method 

 of emptying steam shovel buckets by steam instead of by hand. 



