N'afọ 1758 n'ụbọchị okpomọkụ na Cambridge, England, Franklin na onye ọkà mmụta sayensị ibe ya bụ John Hadley mere nnwale site n'iji ether na-eme ka bọọlụ nke thermometer mercury na-agba mmiri mgbe niile na iji ụfụfụ na-eme ka ether na-eme ka ether na-eme ka ether. Na nke ọ bụla na-esote evaporation, thermometer na-agụ okpomọkụ dị ala, n'ikpeazụ na-eru 7 ° F (-14 ° C). Thermometer ọzọ gosiri na okpomọkụ ụlọ na-adịgide na 65 ° F (18 ° C). N'akwụkwọ ozi ya site na Evaporation Cooling, Franklin kwuru na, "Onye nwere ike ịhụ ohere nke ịkpọrọ mmadụ na ọnwụ n'ụbọchị okpomọkụ nke oge okpomọkụ" Ajụjụ: Gịnị bụ Celsius Celsius okpomọkụ n'oge nnwale ahụ?
18 °C