POWERHOUSE COLLECTION

Floating dairy thermometer

Object No. 85/2033

This is a floating dairy thermometer with a turned wood body. Thermometers were used continuously in the farmer's dairy for monitoring not only the condition of the produce, but also the temperature of the milk room to prevent any spoilage. It was important for milk thermometers to have clearly defined graduation marks which could be observed readily and which were contained within the thermometer's body so as to not allow the accrual of bacteria or hardened milk in the cavities that were formed by external scratches. The milk lactometer tested the quality of milk and comprised a glass hydrometer about 12 inches long, the stem of which contained a scale about 5½ inches (14 cm) long and the remainder featured a bulb and weighted section. Some lactometers contained a thermometer so that the temperature and the specific gravity of the milk could be read. Sets of these tubes were used by farmers for comparing the quality of the milk given by different cows and were floated in the milk being tested. Lactometers have been used since 1891. Carly Todhunter, MAAS Volunteer under the supervision of Margaret Simpson, Curator Dairy operations require careful temperature control. When churning milk to make butter, heating to 60 degrees Fahrenheit is sufficient to slow the growth of bacteria. When making cheese, curds form above 85 degrees, but the added enzyme (rennet) breaks down at higher temperatures. This thermometer, probably made in England between 1900 and 1950, floats upright for hands-free observation. It is marked with red lines and notes at the following Fahrenheit temperatures: 0 ZERO, 32 FREEZING, 60 CHURNING, 85 CHEESE, 150 SCALDING, and 212 WATER BOIL. Debbie Rudder