Geologists sometimes analyze the distribution of materials under Earth's surface, materials such as iron, water, oil, or dry soil. The process they use is called electrostatic exploration. Electrodes are placed in the ground about 800 mm apart. An electric generator is connected to the electrodes and causes them to become oppositely charged. The opposite-sign charges on the electrodes cause electrically charged ions in the matter below the surface to move. The moving ions are detected by equipment on the surface. This helps the geologist decide what type of matter is below the surface. What causes this motion

a maximum–minimum thermometer. the scales are fahrenheit on the inside of the u and celsius on the outside. the current temperature is 23 degrees celsius, the maximum recorded is 25, and the minimum is 15, both read from the base of the small markers in each arm of the u tube. the bulbs are hidden by a plastic housing.

six's thermometer is a registering thermometer which can record the maximum and minimum temperatures reached over a period of time, for example 24 hours. it is used to record the extremes of temperature at a location, for instance in meteorology and horticulture. it was invented by a british scientist james six, born in canterbury, in 1780; [1] the same basic design remains in use.

it is also commonly known as a maximum–minimum, minimum–maximum, maxima–minima or minima–maxima thermometer, of which it is the earliest practical design.

the thermometer indicates the current temperature, and the highest and lowest temperatures since last reset.