l^Q ANNUAL REPORT SMITHSONIAN INSTITUTION, 1936 



The following letter was written to me by a McGill engineering 

 student who was fortunate enough to belong to an Arctic expedition 

 which, after so many years of search by so many navigators, did 

 actually discover the North-West Passage: 



Westmount, February 27, 1931. 

 Deae Sir : 



Yesterday evening you were kind enough to request me to write concerning 

 the aurora. 



I was fortunate enough to be a member of a Survey Expedition to find the 

 channel through the North-West Passage. 



I wintered in the Arctic at the magnetic pole, 70 N., 96 W., during 1928-29. 

 During the period of darkness there were Intense displays of aurora, most 

 frequently seen from the SW. to SE. in dead calm weather, temperature 50° F. 

 below zero. In the Arctic silence, it can be definitely said that whistling 

 crackling sounds accompanied the aurora display. They were also seen several 

 times in the NE. Their effect on radio communication was also marked. Most 

 frequently, north and south communication predominated, and only seldom 

 did the east and west predominate. The communication never showed freak 

 reception in all directions at once, but faded on one and increased on the 

 other. 



It was difficult to get consistent data of the effects of aurora on radio com- 

 munication, even though I tested and communicated daily. The same observa- 

 tions were noted from King William Island during 1929-30. 



(Signed) H. Ross Smyth. 



On the other hand, several of my scientific friends, such as Frank 

 Davies, who has been on both Arctic and Antarctic expeditions, have 

 listened in vain for sounds accompanying auroras. Negative evi- 

 dence, however, is never satisfactory. Others declare that the noise 

 swells and fades at the same instants that the lights increase and 

 diminish in intensity. It is difficult to believe that this could be true. 

 If the aurora is 60 miles away the sound therefrom, if any, would take 

 at 5 seconds for each mile, about 5 minutes to arrive, so that coinci- 

 dence would be more impossible than between lightning and thunder 

 with a flash many miles away. 



Moreover, it must be remembered that sound does not emerge or 

 travel at all well in highly rarefied air such as there is in auroral 

 regions. There is the famous experiment, first made successfully by 

 Robert Boyle, after others had failed, which proved that the sound 

 of a bell does not emerge from within a receiver from which the air 

 is thoroughly pumped. What then do these men hear ? It has even 

 been suggested that they hear the blood surging in their head, or the 

 tinkling of the ice of their frozen breath. We may safely dismiss 

 these suggestions as trivial. It seems more probable that they hear 

 something real in the same sense, let us say, that we hear church 

 bells ring. I may venture to suggest that in dry, cold weather there 

 may be a small brush discharge from snow or bushes somewhat sim- 

 ilar to St. Elmo's Fire, seen on mountains, and sometimes as an 



