It is the function of the official thermometer to indicate the true temperature of the _air_. A thermometer exposed to direct sunshine records its own temperature--i. e., the temperature of the glass and mercury--and nothing else. A thermometer “in the shade”--under a tree, for example--comes nearer to showing the true air temperature; but it is exposed to radiation from surrounding objects and its readings will vary with the nature and location of these objects. The meteorological thermometer is nearly always installed in a kind of latticed screen, or shelter. It is thus largely protected from radiation, while the air circulates freely around it. Only when thermometers are exposed under such standard conditions is it possible to obtain comparable readings of the temperature at different places, so that, for instance, maps may be drawn showing the distribution of this element over a country. The best location for the thermometer screen is a few feet above sod. Many thermometers of the United States Weather Bureau are installed on the roofs of tall buildings; not because this is an ideal location, but because no better is available in the heart of a large city, where, for practical reasons, the office has to be placed. In many small towns the site of the station is such that the thermometer screen (or “instrument shelter,” as it is called in the Weather Bureau) can be placed close to the ground, and at the same time get ample ventilation and be free from the radiation of buildings. In certain large cities the Bureau maintains a branch station in a park or in the suburbs, where a satisfactory exposure for all instruments can be secured. The artificial temperature of a city street is too local and indefinite a thing to be inscribed on weather maps, utilized by the forecaster, or embodied in climatic statistics. As a concession, however, to the demand of the “man in the street” for a record of conditions prevailing in his own sphere, the Weather Bureau has installed in several cities little pavilions in which working meteorological instruments are displayed for the benefit of the public. The thermometers in these so-called “kiosks”--which are modeled, with improvements, after the weather pavilions found at European health resorts--always read several degrees higher in hot weather than the thermometer at the regular Weather Bureau station in the same vicinity. Such records are erratic, at best, and present indications are that the kiosks will eventually be abolished. [Illustration: MAXIMUM AND MINIMUM THERMOMETERS]