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“What would be cool,” she says, “would be to take an infrared light photo or a thermograph of her to see if the spot pattern is still there—but invisible to our eye.”

On such nights the reradiation of energy is not apparent in the traces of the thermographs.

The pressure of the air is measured by the mercurial barometer, and registered continuously by the barograph; the temperature of the air is automatically recorded by the thermograph.

The times when the kite-meteorograph crossed the 700-metre level in ascending and descending were determined from its barograph trace, and the synchronous temperatures and humidities were read from the records of its thermograph and hygrograph.

We cannot know the exact figures to adopt, but the general type of the thermograph for Mars as compared with that of the Earth will remain.