This cylindrical shaped metal flask was known locally as a 'Dudley'. It was made by Ryland, who were a popular manufacturer of domestic products at the beginning of the 20th century.
The flask was used by a miner to carry drinking water underground to have during his shift. In the 1920's it was discovered that miner's would drink up to four pints of water with their break time 'snap' to replace the fluids lost through working in high temperatures underground.
The temperatures that miners were working in at a depth of 3000 feet often reached 100 degrees Fahrenheit. In these harsh working conditions, miners would lose between 3-6lbs of sweat each hour. Drinking lots of liquids and taking salt tablets became essential for their continued health and well being.