35 



the remainder of the day south and south-east, with diminishing force at night. Average 

 direction S. 24° east; mean velocity, 4.12; resultant velocity, 2.44. 



October 3rd. — Changing from south to east shortly after midnight, and blowing 

 more strongly from the east, up to 12 miles an hour till 7 a.m. ; during the remainder of 

 the day blowing strongly, up to 26 miles an hour, from the south-west, shifting at times 

 to the west. Average direction, S. 43 W. ; mean velocity, 16.21 ; resultant velocity, 11.66, 



October 4th. — Strong south-west winds (up to 17^ miles an hour) till 10 a.m. ' r 

 then blowing harder still, up to 25 miles an hour, from the west, shifting to north-west 

 in the afternoon, and diminishing considerably in force at night (6 miles per hour at 11 

 p.m.) Average direction S. 85 W. ; mean velocity, 15.58 ; resultant velocity 13.33. 



October 5th. — North-west winds all day till 7 p.m., when it changed to the west. 

 Average direction ]ST. 54 W.; mean velocity 10.38, resultant velocity 9.89. 



October 6th.— The west wind continued till 3 a.m., then changed to south-west, and 

 at 9 o'clock to south ; in the afternoon south-east, changing to south and south-west at 

 night, and to west before midnight. Average direction S. 19 W. ; mean velocity 6.56, 

 resultant velocity 5.55. The winds were highest from 11 a.m. to 3 p.m., and very 

 moderate at night. 



October 7th. — (The day on which the moths were first observed here.) Very gentle 

 winds west to north-west, varying to north up to noon ; then shifting to north-east and 

 east. A fine, mild day. Average direction N. 10 W. ; mean velocity 2.85 ; resultant 

 velocity 1.09. 



October 8th. — Winds very light, north-east to east up to noon, then south-east and 

 south till 9 p.m., when they changed to the south-west. Average direction N. 52 E.; 

 mean velocity 4.79 ; resultant velocity 3.10. On this day, and the preceding, the moths 

 were found in the lake and washed up on the shore. The southerly winds of the 6 th 

 may have helped the swarm in their flight across the lake, and then the change to 

 northerly and cooler winds may have checked their flight and caused them to drop into 

 the water. 



October 9th. — Winds gentle, south-east, south and south-west. A very mild day, 

 with a little fine rain at night. Average direction of the wind, S. 18 W. ; mean velocity 

 4.50 ; resultant velocity 4.14. 



Mr. Carpmael also very kindly sent me a table of the direction and velocity of the 

 wind at Kingston during the same period taken at the usual hours of observation, viz., 

 7. a.m., 3 p.m., 10 p.m. This will assist us as regards the appearance of the moth at 

 Ottawa : — October 1st, winds south-west, mean velocity about 7 miles. Oct. 2nd, south 

 in morning, south-west in afternoon and evening ; mean velocity 2 miles. Oct. 3rd, east 

 in morning, south-west afternoon and evening ; mean velocity 9 miles. Oct 4th. south- 

 west in forenoon, south in afternoon, north-east at night ; mean velocity 9 miles. 

 Oct. 5th, north in the morning, north-west in afternoon, west at night ; mean velocity 

 about 4 miles. Oct. 6, west in morning, south-west in afternoon and evening ; mean 

 velocity about 5 miles. Oct. 7th, west in morning, south-west in afternoon, and north- 

 east at night ; mean velocity about 4 miles. Oct. 8th, north-east at each observation ; 

 mean velocity 5 miles. Oct. 9 th, north-east in morning, south-west in afternoon and 

 evening ; mean velocity 3 miles. 



From the above we gather that the direction of the wind was very much the same 

 at Kingston as at Toronto, but the velocity was considerably less at the former station. 



In addition to the foregoing, I have obtained through Dr. Hamilton a table of 

 similar observations made at Pittsburg, Pennsylvania, by the Signal Service Observer of 

 the XJ. S. army. This will give us some idea of the prevailing winds to the south of 

 us, and by comparison with the observations at Toronto and Kingston, will help us in 

 the formation of some conclusion regarding the migration of the cotton moth. 



The Pittsburgh observations were taken at the same hours as those at Kingston, and 

 are, briefly, as follows : — Oct. 1st, winds south-west throughout the day ; mean velocity 



