Mean maximum 60.9 Mean minimum 49.7 _Range._ Monthly 31.0 Mean daily 9.3 Greatest daily (19th) 15.5 Least daily (23rd) 1.5 SIX INCHES. Monthly mean 56.3 _Extremes._ Maximum (31st) 66.0 Minimum (6th and 7th) 43.0 Mean maximum 56.7 Mean minimum 53.2 _Range._ Monthly 23.0 Mean daily 4.65 Greatest daily (8 and 19) 8.5 Least Daily (5th) 1.0 TWELVE INCHES. Monthly mean 55.6 _Extremes._ Maximum (31st) 64.0 Minimum (6th and 7th) 46.0 Mean maximum 56.6 Mean minimum 54.4 _Range._ Monthly 18.0 Mean daily 2.18 Greatest daily (8th) 4.5 Least daily (3rd and 20th) 0.0 TWENTY-FOUR INCHES. Monthly mean 53.1 _Extremes._ Maximum (31st) 58.0 Minimum (6th and 8th) 48.0 Mean maximum 53.4 Mean minimum 52.8 _Range._ Monthly 10.0 Mean daily 0.48 Greatest daily (23rd) 2.0 Least daily (on 12 days) 0.0 [Illustration: FIG. 14. SOIL THERMOMETER—Whitney and Marvin. ] =115. Method of Whitney and Marvin.=[77]—The thermometer devised by Whitney and Marvin is shown in Fig. 14. The principle on which this modification depends is as follows: A mercurial thermometer of the ordinary construction is liable to give wrong indications of the temperature because it is difficult to determine the temperature of the column of mercury from the bulb to the surface of the ground. To avoid this source of error the thermometer figured was constructed. The bulb of the thermometer is made quite small and a slender portion of the stem extends into its spherical portion. The top portion of the thermometer stem does not differ in any essential respect from the stem of an ordinary thermometer.