Dreyfuss modernized the appearance of Honeywell’s thermostats in the 1930s; among the first was the Chronotherm, which incorporated a “digital” clock into its display. Dreyfuss was frustrated, however, that rectangular thermostats never seemed to hang squarely on the wall. Work began on a round thermostat in 1940. Placing all the elements in a circular form was more difficult than it first seemed; attempts to make a curved thermometer were especially problematic. World War II halted the development program but helped provide technical solutions. The substitution of a bimetallic coiled thermometer and use of a sealed mercury switch eliminated problems with contamination from dust. By 1953, the thermostat was refined into its now-familiar form, refered to simply as the Round. Its low price and ability to fit most situations has made the Round one of Dreyfuss’s most successful designs. His continuing emphasis on ease of use and maintenance, clarity in form and function, and concern for end use helped make Honeywell a leader in the field of controls for both domestic and industrial environments.