ABSTRACT OF PROCEEDINGS. xxili- 
that birds of certain form ascend when there is a horizontal wind, 
whereas according to their weight and the velocity of the wind 
they ought to descend. The act of ascending is termed “ Aspir- 
ation.” Numerous sections showing the profile of wings have 
been published from time to time, and Mr. O. Chanute, c.z., of 
Chicago, U.S.A., has pointed out the distinction between the 
soaring and flying wing profile. The writer, whilst experimenting 
with metal bent similarly to a soaring wing, has discovered— 
1. That the profiles of a soaring bird’s wing and pieces of metal 
of a somewhat similar curve, are such that they generate vortices 
on their concave surfaces when the chord of the curve makes a 
negative angle with the direction of the wind. 2. All the con- 
cave surfaces are in contact with air that is moving towards the 
mean direction of the wind. 3. That the mean pressure on the 
concave surface is higher than that on the convex side. 4. That 
the chord of the curved metal may make a negative angle of ten 
degrees with the direction of the wind, and still have a higher 
pressure on the concave side than on the convex. ‘The practical 
etfect of these discoveries is that birds, and therefore flying 
machines of suitable form may rest on an air current, generated 
by their shape, that is ascending and moving towards the mean 
direction of the wind; and that the aggregate normal pressure 
exerted by the wind ona soaring wing is not upwards and inclined 
to leeward, but upwards and inclined more than 10° to windward. 
3. “On ‘Grey Gum,’ Eucalyptus punctata, DC., particularly in 
regard to its essential oil,” by R. T. BAKER, F.L.S., Assistant 
Curator, and.Henry G. Surru, F.c.s., Technological Museum, 
Sydney. 
The paper deals with several forms of this species of Eucalyptus, 
which extends over the greater part of the coastal districts and 
also over the Dividing Range. In addition to the economic and 
Systematic notes the histology of the leaf was also given and 
illustrated. The essential oil, obtained by the authors was 
shown to be of excellent quality, whilst the yield was also very 
good. It contained (unrectified) 46 to 64 of Eucalyptol and a 
