sentences:  While the new lens was being installed, the light from a third-order lens was exhibited atop a temporary tower erected near the lighthouse; it was later sold at auction.The Highland Light was then the most powerful on the east coast of the United States.Two four-horsepower oil engines with compressors operated by an engine fueled by kerosene, were added to ensure that the fog signal could be activated within ten minutes instead of the previous 45.