Our polar flight

by Roald Amundsen; Lincoln Ellsworth

As often as we got rid of the low clouds, Mr. Calwagen sent up the pilot balloons for observing the wind’s direction and strength. These observations were of the greatest value for judging the weather conditions, and I will therefore mention them in a few words here. The observations took place as follows: A colored rubber balloon is filled with water gas until it is one-half meter in diameter. One weighs its buoyancy and thereby knows the speed with which it will rise into the air. After the balloon has been sent up it is observed through glasses which have graduated scales for calculating necessary horizontal and vertical adjustments—this is called a theodolite. The theodolite’s indications are read and noted each half minute whilst the balloon rises. Afterwards it is possible to reconstruct the course which the balloon has followed, and to ascertain hereby the course of the wind at the different heights.

It was not always easy to find a suitable place to set up the theodolite. On board the “Fram” it very often happened that the balloon after some minutes got behind the ship’s masts or funnel, and thereby was lost from view. On the ice in the fjord it was generally possible to find a good spot with the exception of the days when there was a heavy swell on the water outside, which also set the fjord ice making slight undulating movements, and which were disturbing enough when it was a question of reading one-tenth of a degree on the theodolite. Near Danskeöen, where there was no useful fjord ice, Mr. Calwagen had to be rowed ashore for each pilot observation in order to have firm ground below the theodolite. Generally he chose the little islet “Likholmen,” where he could sit and have an uninterrupted view on all sides. When the “Fram” went out to get fresh water-ice from an iceberg which had got aground, Mr. Calwagen was there immediately and set his apparatus up on the iceberg. This is probably the first time that pilot balloon observations have been made from an iceberg.

With the execution of all these pilot balloon observations, under conditions which were continually changing and often difficult,[*] Mr. Calwagen had to use all his care and all his skill. It can certainly be said that he made use of every possibility imaginable in order to collect data which might be helpful in supplementing the expedition’s weather forecasts.

[*] After having sent in this report, the sad news had just been received that Mr. Calwagen has been killed in a flying accident at Kjeller, near Oslo, on the 10th of August, 1925. Immediately after arriving home from Spitzbergen he commenced to work on that branch which he was the first to start in Norway, namely, the reading of the atmospheric conditions by self-registering instruments installed in aeroplanes. In the course of the last year he has personally taken part in many flights in order to complete the registering-dials of the instruments from his own observations. The accident happened during such a flight, just when he was engaged in collecting observations for determining the atmospheric belts.

All who were with the expedition will no doubt remember Mr. Calwagen as a practical man, helpful, impulsive, bubbling over with merriment, capable but at the same time possessed of a modesty which was the natural result of his noble altruistic nature. We all feel very grieved at such a man’s death.

When it was necessary to have two men for the pilot balloon ascents, Mr. Calwagen got excellent assistance from ice-pilot Ness, who, according to what he himself said, was only too glad to be employed a little on such an occupation during the long hours in which “Fram” lay idle, not giving him enough to do.

Altogether sixty-two pilot balloons were sent up between the 15th of April and the 29th of May. It was possible to follow one of them through glasses to a height of 10,500 meters. This, however, was only possible because there was very little wind all the way up. Generally the wind was so strong that the balloon was lost sight of at a much lower height.

It will lead us too far into scientific spheres to describe all the methods used in determining the weather conditions from weather-charts and from observations which were made. I shall have to content myself by just mentioning the main principles which must be taken into consideration when choosing the starting day.

It is the general experience that the regions which have low air pressure mostly have cloudy weather and rainfall, whilst places with high air pressure have fine weather with a clear sky. The point was therefore to avoid conditions where a depression was moving towards the Pole.

In order to be pretty safe from bad weather it was necessary to choose a high pressure condition. Further, the high pressure would have to lie north of Spitzbergen so that the aeroplanes should not fly out of good weather directly into bad on the way north. A high pressure condition over the Pole would necessarily bring with it northeasterly winds and cold weather in Spitzbergen. This northeasterly wind would (at West Spitzbergen) be an off-shore wind and therefore would signify clear weather. Along the north coast of Spitzbergen the weather would be more doubtful, with a northeast wind which would cause the air to rise up against the hills and form clouds. But these cloud-masses on the north coast would very often only stretch out over a limited area which the flyers could pass in a short time, preferably by flying over the clouds.