particles disappear, but an excessively thin coating of grease, deposited with the carbon from the flame, remains and the line traced by the point of the pen is clearly visible in it with a magnifying glass.
"A notable instance occurred during one of my earliest experiments in the Mediterranean in 1904. An instrument was lost to the northward of Corsica, and was found on the shore of Provence fifteen days later. The curves traced in the greasy film on the recording drum were still perfectly visible, and were utilised with the others in Professor Hergesell's laboratory.
"A kite operation, at a height of 3,000 to 5,000 metres, lasts almost the whole day, and the ship, which must at times steam full speed (the yacht Princesse Alice attains a maximum speed of 13 knots) in order to enable the kites to pass through zones of light wind or of calm, may easily cover a distance of 50 or 60 miles during the operation."
But, besides kite observations at high altitude, the Prince of Monaco has made some very remarkable investigations in the Arctic Regions by means of small balloons, which he terms "ballons-sonde," which carry up instruments, and which, by several different ingenious devices, he recovers again. He has also made many valuable observations, by means of pilot
