34 THE ESSEX NATURALIST.
Sallow (X. ocellaris). This is attached to the poplar (Populus
nigra) and was found towards the middle of September very near
the Suffolk boundary on the banks of the Stour. Like many
of its congeners of the Xanthia tribe this moth likes to hide
among dead leaves in the daytime, and the most successful way
of capturing it is to tap any bunch of dead leaves that may be
found over a net. A visit to St. Osyth Beach early in October
brought the active collecting season to a close. Larvae of the
Sand Dart (A. ripae) are usually to be found here in numbers
at this time, buried in the sand at roots of Sea Campion, Sea
Rocket, etc., hybernating as larvae, but this season they were
rather scarce.
Altogether the season of 1932 was not a bad one, the weather
was kind on the whole, though the spring was late. It has
certainly not been a year for migrants, very few Vanessa cardui
were noticed, and not many V. atalanta. The Clouded Yellow
(C. edusa), although recorded in small numbers from the South
Coast, has not been in evidence in Essex.
BOTANY IN RELATION TO THE STUDY OF
TIMBER.
By FRANK W. JANE, B.Sc., F.L.S.
TIMBERS differ widely in their physical properties and
structure, and it is these features which, to a great extent,
determine the uses to which a wood can be put. The results of
mechanical tests enable us to predict the behaviour of a timber
under various stresses, and this, coupled with an examination
of the gross and microscopic features, helps in assessing its
value for a particular purpose. This work is of great value at
the present time, when many new or little known timbers are
appearing on the market, and as some of these are used as
substitutes for better known woods, or at least are marketed
with similar trade names, the accurate identification of woods
becomes a matter of importance.
For this purpose a knowledge of the structure of wood is
essential. Grosser anatomical features often suffice to identify
certain woods, but in dealing with closely related timbers it