. Boston Logan International Airport environmental impact study. Logan International Airport; Airports; Environmental impact statements; Harbors; Oceanography; Pollution; Pollution; Transportation. 264 ALFRED C. REDFIELD. Figure 3 ber pressure tubing may be led down the mooring rope to connect it with an orific in the mooring block. Either ar- rangement can be used where a suit- able wharf is available. In using the instrument from an anchored boat, a mooring must be used which will not drag or foul with the swinging of the boat. The mooring devised is illustrated in Figure 1. It consists of a
. Boston Logan International Airport environmental impact study. Logan International Airport; Airports; Environmental impact statements; Harbors; Oceanography; Pollution; Pollution; Transportation. 264 ALFRED C. REDFIELD. Figure 3 ber pressure tubing may be led down the mooring rope to connect it with an orific in the mooring block. Either ar- rangement can be used where a suit- able wharf is available. In using the instrument from an anchored boat, a mooring must be used which will not drag or foul with the swinging of the boat. The mooring devised is illustrated in Figure 1. It consists of a concrete block 14 in. on a side and 9 in. high in the top of which a short length of chain is embedded. The upper part of the block is beveled to avoid fouling. A piece of %-in. brass pipe is embedded in the block—parallel with its under surface and just below the bevel. The rubber pressure tubing is lashed at intervals to the mooring rope and to the chain at its junction with the block. Its end is passed into the brass tube and lashed in position. This mooring, which weighs about 180 lb, has held a 12-ft skiff containing the gage in an exposed position and in strong tidal currents for more than a month without dragging or fouling. Figure 2 shows the assembly mounted on a marsh bank. A typical record obtained in a salt marsh creek is illustrated in Figure 3. Records continuous for 29 days have been obtained during two periods with the in- strument mounted on shore and during two with the gage installed in a moored boat. Under ordinary harbor conditions the in- strument requires no damping to eliminate the effects of short period surface waves. The effect of wind waves under extreme conditions is illustrated by the inset in Figure 3, a record made in Great Harbor, Woods Hole, during a gale. Oscillations of longer period are recorded as shown in Figure 3 during the falling tide. In testing this type of gage from a pier at Adantic City, the U. S. Coast and Geodetic Survey found
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