sewer outfalls, piers and causeways. (c) Control for Preliminary Surveys. Existing traverse points of the Joint Task Force Seven Survey will be recovered and used as the basis of preliminary horizontal control. These points will be supplemented by additional traverses where required. Vertical control for these preliminary surveys will be obtained by simultaneous observations of tidal variations at the various islands. Will be set up for this purpose. Tide staffs Differential corrections will be made to es=- tablish a datum common to the islands involved, and adjusted to mean low water Springs by applying the tide prediction for the observed time as given in the Tide Tables of the Pacific Ocean 1919. Personnel. Assuming that required materials and equipment will be avail- able on arrival and that efficient inter-island transportation will be provided, a four man survey party is recommended for the initial surveys. This party will consist of a Chief of Party, Instrument Man, and two Chainmen. It is anticipated that survey operations involved in establishing horizontal and vertical control, and in obtaining the basic information for design can be completed in approximately forty-eight party days of workable weather. This could be reduced by adding manpower, but not in direct ratio. Supplementary Services of Chief Surveyor and Party. Consideration should be given to additional work which could be accomplished by the Survey party during preparation period, which would reduce later costs to the project. Sug- gested additional work would include the following: (a) Establish secondary and construction controls on the pro=ject islands well in advance of actual construction. This would consist of most of the work outlined in the later. IV - 10