One of the chief objects of the Expedition was to collect information as to the distribution of temperature in the waters of the ocean. It was therefore important to observe the temperature, not only at the surface, but at the bottom, and at intermediate depths. The determination of the temperature of surface water is simple. It suffices to collect a sample in a bucket, taking care that it is not contaminated with water, either from the scuppers, or from the discharge pipes of the engine, to plunge a good thermometer into it, and observe it carefully. The thermometers 1 supplied for this purpose were very sensitive, and divided into single degrees of Fahrenheit's scale. For the purpose of observing the temperature of the waters below the surface in lakes and seas, three classes of thermometers have been used-namely, ordinary thermometers, self-registering thermometers, and electrical thermometers. [NOT CONTROLLED OCR]