intervals:
two days, three days, five days, one week, etc., until they are quite
dry. The length of time required for pressing and drying depends upon
the quantity of sap in the plants and also upon the dryness or humidity
of the atmosphere.

~Mounting.~--When dry, the specimens are mounted on sheets of heavy white
paper. These sheets are cut to a standard size, eleven inches by
fourteen inches, or sheets of half this size, namely, seven inches by
eleven inches; are permissible. The best method of attaching the plant
to the sheet is by pasting narrow strips of gummed paper across the
plant in such positions as will serve to hold all parts of it in
position.

~Labelling.~--The name of the specimen, the date of collection, the place
from which collected, and the name of the collector are to be neatly
written in a column in the lower right-hand corner of the sheet. Printed
labels which are pasted on this corner of the sheet are also used.

Collections of leaves may be prepared by the same process as that given
for plants. Leaves will retain their autumn tints if their surface is
covered with varnish or paraffin, which will prevent the admission of
air.

To cover with paraffin dip the leaf for a moment into melted paraffin.

CHAPTER II

PHYSICAL SCIENCE PHASE OF NATURE STUDY

INSTRUCTIONS AND GENERAL METHOD

The preceding portions of this Manual dealt with living things. There is
another phase of Nature Study which has a more direct relation to the
physical sciences, Chemistry and Physics, two subjects that are
essentially experimental in their methods.

Although the lessons that follow are grouped in one portion of this
book, the teacher should understand that he is to introduce them into
his work as the occasion demands. They may be used to throw light on
other parts of the school work. The experimental method is somewhat
advanced for young children, hence no lessons are outlined for Forms I
and II. In ungraded schools, Forms III and IV may be combined for the
subject. It will be found most convenient to take this portion of the
Nature Study during the winter months.

VALUE OF SUCH LESSONS

1. They are _interesting_, hence there is attention. The senses must be
alert, hence pupils are trained to observe accurately.

2. After the experiment comes the inference, hence reasoning powers are
developed.

3. They enable the teacher to make exceedingly _concrete_ some very
difficult abstract principles.