THE PLANE-DROPPER. 



41 



Experiments to determme the time of Jailing of two sets of planes, one above the other {second series). 



Table IX.— August 22, 1889. 



F. ^^'. Very, Conducting experiments. 



Barometer, 731. 8 mm. ; mean temj^erature, 23°.9 C. ; wind, light. 



Dimensions and aspect of 

 planes. 



JS 



IS 



3^ 



IS 



15 



15 X 4 inches (38.1 x 10.2 



cm.). 

 Double pair of planes. 4 



inches apart. 

 Total weight, 942 grammes. 



Same planes, 2 inches apart. 



Same planes, 6 inches aj^art. 



2 ^ '^ 



S--« 8 

 o ° ■' 



o 



C "5 'd 





■ce-5. 



W 



2.60 

 2.65 

 2.60 

 2.65 

 2.65 

 2.60 

 2.50 

 2.50 

 2.65 

 2.65 

 2.65 



2.35 

 2.45 

 2.60 

 2.60 

 2.95 

 2.75 

 2.70 

 2.65 

 2.60 

 2.65 

 2.75 



3.30 

 3.30 

 3.35 

 3.30 

 3.00 

 2.95 

 3.00 

 3.00 

 3.15 

 3.20 



0.0 

 0.0 

 23.7 

 23.3 

 23.7 

 23.3 

 23.3 

 23.7 

 24.6 

 24.6 

 23.3 

 23.3 

 23.3 



26.2 

 25.1 

 23.7 

 23.7 

 20.9 

 22.4 

 22.8 

 23.3 

 23.7 

 23.3 

 22.4 



18.7 

 18.7 

 18.4 

 18.7 

 20.5 

 20.9 

 20.5 

 20.5 

 19.6 

 19.2 



° o 



0.69 

 0.62 

 1.68 

 1.70 

 1.70 

 0.70 

 1.00 

 0.75 

 0.50 

 2.20 

 6.15 

 0.90 

 1.20 



1.60 

 1.20 

 1.90 

 1.30 

 4.15 

 0.70 

 5.80 

 0.72 



0.70 

 0.50 



1.70 

 1.20 

 1.50 

 1.30 



14.80 

 1.00 



14.20 

 1.10 

 0.75 

 0.75 



Remarks. 



Fell, then soared. 

 Fell slowly. 



Soared, then fell. 



Gradual fall, l>ut very slow. 



Stayed at top. 



Fell very slowly. 

 Fell verj- slo-\\-ly. 



Result : It is certain that any angle greater tho.n + 1° (with planes 6 inches apart) would 

 produce soaring, and as the error of verticality in this day's observations probably does not 

 exceed 1° during motion, we may take about 2° as the soaring angle for the speeds used. 



6 



