Eighteenth. All instruments for surveying or for testing materials, when not in use, must be kept in their cases or boxes in the Resident Engineer's office. No transits or levels should be left set up around derricks or machinery where there is danger of their being struck by the said machinery or by teams, unless someone is left to guard them.

Nineteenth. The Resident Engineer must be careful not to abuse in any way the rather arbitrary power that is placed in his hands; but, on the other hand, he must not fail to act promptly in exercising the authority conferred on him, if it be necessary to do so in order to protect the interests of his client or those of his superiors.

Twentieth. See that all materials are properly stored and kept in good condition until used in the construction; and make sure that the contractor takes every precaution to prevent injury to them from fire or flood, no matter whose property they may be. If practicable, they should be insured.

Twenty-first. Make sure that no damage is done to structural steel or reinforcing bars through carelessness in handling or unloading.

Twenty-second. See that all wooden paving-blocks are risked up in compact piles and covered so as to prevent checking; and, as all creosoted timber is very inflammable, take every precaution against its being injured by fire.

Twenty-third. Make sure that all cement is properly protected against the weather; and that no injured cement is allowed to remain on the job.

Twenty-fourth. Take great care to avoid accident in the storage or use of explosives; and see that the proper charges are used.

Twenty-fifth. Make sure that all falsework and forms—in respect to both design and quality of materials—are fit for the purpose to be served; and take the necessary steps to prevent unsightly bulges and offsets in concrete surfaces due to the yielding of forms.

Twenty-sixth. In sinking cribs or caissons do not permit the contractor to allow them to get materially out of position or tipped; but check constantly for line, elevation, and verticality until all danger of the occurrence of such errors of any magnitude is past.

Twenty-seventh. Look carefully to the building up of cribs and caissons; because, if they become badly warped or twisted, much needless expense and delay will be involved.

Twenty-eighth. Watch carefully the depositing under water of all concrete so as to make sure that it is not injured in the process of placing.

The preceding instructions, of course, could readily be extended by entering more into detail, and it is true that the Resident Engineer should study and follow closely many other directions, both written and oral, given him by his superiors; but enough has already been said in this chapter to indicate the necessity for a proper application to fieldwork of the principles of economics, what the said principles are, and how they should be utilized.