INVESTIGATION OF THE UPPER ATMOSPHERE BY MEANS OF KITES, 79 



would be obtained, from which the two unknown quantities, tempera- 

 ture, and height can be determined. I hope to perfect this method, 

 since there are many occasions on which a kite and a couple of glass 

 tubes might be risked when one would hesitate to send up instruments 

 costing 20^. 



The apparatus abo^^e described is now in use every day when the 

 wind is suitable, but there seem to be very many days during the summer 

 when a sufficiently strong wind does not occur. A velocity of about 

 fifteen miles per hour is necessary, force i on the Beaufort scale ; but the 

 upper limit at which the kites will fly has not yet been determined. 



II. — Addendum, August 22. 



Up to August 20 sixty-eight flights have been obtained, as shown in 

 the following table : — - 



