Poldark has not been commissioned for a third series.
A Kingston valve is a type of valve fitted in the bottom of a ship 's plating that connects the sea to the ship 's piping and storage tanks .. valve. valve. ship. ship. sea. sea. A Kingston valve is a type of seacock .. valve. valve. seacock. seacock. It is arranged so that , under normal operating conditions , sea pressure keeps the valve closed .. valve. valve. sea. sea. When opened from the ship 's interior , the Kingston valve allows sea water to enter the tank .. valve. valve. ship. ship. sea. sea. The mechanism is named after its inventor John Kingston -LRB- 1786-1847 -RRB- , an English engineer .