NORTH POLE OF THE WINDS 



essential thing is to recover the balloon and its in- 

 struments, for otherwise not only has one wasted 

 his time but incurred a loss of about $150 of equip- 

 ment with each ascent. 



The Rossby deflating device, which we hoped 

 would make possible the use of the registering 

 balloons in Greenland, consisted of a light wooden 

 rod projecting from the valve of the balloon and 

 along which a rubber band is stretched. The valve 

 of the balloon is kept open by a small spiral spring 

 except when the pressure from this rubber band 

 acting on the delicate spring keeps it closed. A 

 fuse is now so attached that it will burn off the 

 elastic band and open the valve at a height deter- 

 mined by the length of fuse taken. As the balloon 

 rises in the air the smoke issues from the fuse until 

 the band is reached and the valve opened. 



It was, of course, necessary to work with such 

 balloons only when the air was calm, and it was 

 further necessary in our location to provide a float 

 beneath the box of instruments so that if the bal- 

 loon descended over the fjord the instruments 

 would be kept afloat until rescued. Mr. Fergus- 

 son made a small float consisting of three pilot 

 balloons inflated to a diameter of about eight inches 

 and this float was suspended beneath the aluminum 

 box which enclosed the delicate instruments, known 



54 



