The ornamental design for the body of thermometer assembly, as shown and described.
FIG. 1 is a front elevational view showing a thermometer assembly of my design; with the glass thermometer tube being shown in ghost line.
FIG. 2 is a left side elevational view thereof; with mounting brackets and the glass thermometer tube being shown in ghost line. The right side elevation is a mirror image thereof.
FIG. 3 is a rear elevational view thereof; and,
FIG. 4 is a bottom view thereof, the top view being substantially identical.