Page:Polar Exploration - Bruce - 1911.djvu/216

212 continuously the ever-ascending balloon with the theodolite telescope, Captain Carr and I were reading the vertical and horizontal limb of the theodolite and recording our synchronous observations. Knowing its ascensional force Professor Hergesell was able to calculate the course and altitude of the balloon, which reached a height of 26,050 feet, where a W.N.W. wind was blowing at the rate of 28 metres per second. The weather was clear, calm, and sunny, and gave a very good opportunity to carry out this series of observations in a thoroughly satisfactory manner.

During this interesting investigation of the atmosphere the Prince of Monaco was much hampered in carrying out his programme by persistent fogs over the sea to the westward of Spitsbergen, although in the bays and on the land the weather was magnificent. Thus the dispatch of "ballons-sonde" which the preliminary experiments in the Mediterranean had rendered perfect of execution was stopped by this insurmountable difficulty. Twice only was it possible to dispatch them. Nevertheless, the information received was very valuable, since the registering instrument brought back curves from an altitude of 24,600 feet in latitude 78° 55′ N.

In this Arctic voyage the Prince had to resort to a new method on account of the