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442.072
bed near its middle, a series of outlet-pipes leading from the said drain to one side of the road-bed, means for closing the outer ends of the said outlet-pipes, and branch air-pipes ex- 5 tending transversely from one side of the road-bed to the said drain, the outer ends of the said pipes being adapted to connect with an air-pump for pumping the air out of the drain, substantially as shown and described. Io 3. In a system of road-drainage, the combi- nation, with a drain arranged longitudinally
under the road-bed near its middle, of a branch air-pipe extending transversely and connected with the said drain, the outer end of the said air-pipe being adapted to connect m with an air-pump to discharge the air from the drain, substantially as shown and described. ALEXANDER MII'CIIELL. \VTitnesses: WALTER ANDERSON, JNO. P. SHERIDAN.