Irish Famine (1740–41) affect economies, energy sources, and politics. Although no barometric or temperature readings for Ireland survive from the Great Frost, a scattered few records survive from Englishmen who made personal readings. The mercury thermometer was invented 25 years earlier by the German pioneer Daniel Gabriel Fahrenheit. Indoor values during January 1740 were as low as . The one outdoor reading that has survived was stated as "thirty-two degrees of frost." This did not include the effects of the wind chill factor, which would have been severe. This kind of weather was "quite outside the Irish experience," notes David Dickson, author of
Breguet's thermometer connected to an index, which projects over a graduated circle (b). The expansion of silver with temperature is almost twice as great as platinum, with gold being in somewhere in between. The result is that a temperature rise or fall will cause a corresponding twist in the spiral, moving the index. The slip of gold in between is to prevent "sudden starts". Breguet's thermometer Breguet's thermometer, also called a spiral thermometer, is a type of thermometer which uses the expansion of metal under heat to produce a measurement more sensitive, and with a higher range, than both mercury and air