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Alexander Mitchell's Legacy:

After his death in 1868, Mitchell's screw-pile invention lead to the construction of lighthouses, piers, and other offshore structures and is still used in construction today. In 1884, he was awarded the Telford silver medal from the Institution of Civil Engineers. Mitchell's invention was used in the construction of bridges in India, in the Bombay, Baroda, and Central India Railway, allowing a system of telegraphs to be set up, which allowed for the nation to stay modern and communicate quickly over long distances. There was a decline in the use of the Screw-Pile also known as helical piles, in the early 20th century, but it has seen a resurgence in use since the late 1980s and early 1990s. There has been a lot of interest in the use of Mitchell's screw-pile in recent decades, as it is being used in foundations of offshore renewable energy locations. The screw-pile has been adapted throughout the years to become as efficient as it possibly can. The current installation relies on a pitch-matched installation manner to avoid disturbing the soil in a way that would limit the effect of the capability at which the piles can withstand. One notable adaptation to Mitchell's screw-pile invention is to enhance the capacity by adding a helix plate to the pile shaft. Other research in improving the screw-pile found that regardless of the soil being used, increasing the helix number increases the compression capacity. They continue to be used because of their many advantages, such as minimal easy installation, required equipment, minimum produced noise, and vibration during installation, cost-effective, removability, and reusability. There are eleven of Mitchell's lighthouses still standing today, many of which can be found in the United States. Such as, the Roanoke River Light found in North Carolina, or the decommissioned Seven Foot Knoll Light found in Maryland at the mouth of the Patapsco River. The Spit Bank Lighthouse, in Cork, is also still standing today.