Letter from Saloman Moses Drach, Chelsea to Edward Sabine Refers to Drach’s plan of observing the thermometer at six hourly intervals leading to the nearest mean daily temperature, as confirmed by the Toronto observations 1842-1848. Includes a table showing the sums for the hours, means for the hours, and errors. Drach suggests a series of observations to be taken at sea every six hours. 7 november 1853