456 S. H. BARRACLOUGH. 
aluminium and steel on the other. These two metals are chosen 
as aluminium is no doubt a rival to magnesium on the score of 
lightness, and steel on account cf its strength. 
The form in which the comparison is made is one very com- 
monly adopted. 
tper |‘T ie ee Aerial Length of a bar that just | 
Metal. Bis ye: ths.| ths. | supports its own weight. 
Magnesium ith 107-6 | 24,000 82,119 feet 
Aluminium 168 26,000 22,285 ,, 
| 
Hard Struck Steel 490 
78,000 | 22,922 °,, 
The figures for the aluminium and the steel are taken froma 
paper on “The materials of aeronautic Engineering,” read by 
Dr. Thurston at the Engineering Congress, Chicago, 1893. 
Nore on some PRODUCTS rrom tHe FRUIT or PITTOS- 
PORUM UNDULATUM ayv From tHe LEAVES or THE 
PEPPER TREE (Schinus molle). 
By R. Ture.ratt, m.a., Professor of Physics, University of Sydney. 
[Read before the Royal Society of N.S. Wales, December 4, 1895.] 
Pittosporum undulatum, so common in the bush around Sydney, 
not only produces flowers of exquisite scent, but bears an abundant 
crop of fruit. The fruit consists of slightly oval berries of about 
one centimeter in diameter. During the month of May these 
berries pass from a dark green to a bright orange hue, and in the 
following month usually split longitudinally, displaying a mass of 
dark coloured seeds or pips buried in a dark red mass of a pitch 
like substance. If the fruit is gathered when just ripe the pitchy 
mass is lighter in colour and I think rather more voluminous than 
is afterwards the case. Long before the fruit is ripe the pericarP 
and epidermis become more or less saturated with oil. The 
