82 



of these two borers can be determined only by \ie\ving the interior of an exposed 

 timber, cutting into the wood is required; this must alwa>'s be avoided if possible 

 with protected piling. A convenient substitute is the test block. These can be exposed 

 in any number and at any point and if properly used will give a reliable indication 

 of attack. 



Conditions under which test blocks should be placed have already been discussed 

 under the subject of Infestation (p. 56), with reference to the instructions for sys- 

 tematic preparation and exposure of such tests in Appendix B. 



The Problem of Workmanship 



The great body of adverse influences affecting a marine structure, together with 

 the exacting conditions of its operation, olniously require that the best materials and 

 workmanship be used in its construction. Vet, what is "best" must always be con- 

 ditioned by what is practicable; it is easy to conceive of a substructure capable of 

 meeting all requirements, yet which would be impossible of general use because pro- 

 hibitive in cost of construction. The best of workmanship can only be, therefore, the 

 best that can be economically justified. In other words, procedures must be developed 

 whereby successful results will be obtained with the best workmanship that is feasible. 



It has already been noted that many substructure materials which have failed 

 could have been successful had proper workmanship been used. An instance of this is 

 afforded by the so-called Holmes cylinder, consisting of one or more timber piles en- 

 cased in a cylinder of concrete. This type, built in Pier 5 at San Francisco in 1896, is 

 still serving after 29 years, whereas many complete wharves built subsequently with 

 the same type have long since failed and been rebuilt with other types. The life of 

 wharves built with this type, with the exception of Pier 5, ranged from about 7 to 15 

 years. Pier 34, built in 1910 with a substructure of single piles encased in concrete, is 

 still serving in perfect condition after 15 years. These two instances of successful 

 results have been attributed to careful methods of placing the concrete, the several 

 unsuccessful results to faulty methods of a\'erage workmanship. The practical diffi- 

 culties involved in securing successful results ha^•e caused the type to be at least 

 temporarily abandoned, although it is not inherently faulty (fig. 29). 



Another phase of the problem of workmanship concerns especially the common 

 handling of jobs by contract. Contract crews are even more likely than the owner's 

 own employees to be ignorant of the damage caused by carelessness, and thoughtless 

 of loss thus entailed. Besides this, if specification requirements in respect to work- 

 manship are unusually difficult or onerous, the contractor may fail to carry out the 

 work accordingly, through his own failure to understand, his inability to train his 

 men, or his deliberate intention. Much can be done to help, by personal explanation 

 and discussion, as a supplement to specifications or instruction orders, especially 

 with respect to care in handling, and it is time well spent for an engineer to seek in 

 this w^ay to enlist the cooperation of rafting and construction crews. Improved methods 

 of inspection are increasingly eliminating deliberate evasion of specification require- 

 ments and concealment of shoddy work; but the problem of perfunctory cjr cursory 

 inspection still requires eternal vigilance. Inspection of piling in the gins, which has 

 been recommended, takes more time. It is thus likely both to be opposed by contrac- 

 tors and evaded by inspectors, and can be secured only by continuous insistence. 

 However, its results are worth the cost. 



Additional cost, if any, must of course be paid for; but if requirements are plainK' 

 stated in the specifications upon which bids are taken, all bidders are on the same 

 footing. Contractors cannot afford to scrap valuable material, such as piling, which 



