sheet lightning

In most very warm days in summer the thermometer stands above 70 degrees on the scale of Fahrenheit, about the centre of the county; in the summer of 1811, it stood repeatedly above 80°; and on the 25th of May, 1807, during the time when the sheet lightning of tropical regions appeared, about three in the afternoon, it stood at 92° in the shade within three miles of Moffat!