s of the blades the skates are removed and the file is
drawn along the sides to remove the

[Illustration: Filing a Curved Surface]

burr. Skates filed in this way have flat surfaces with sharp
edges.

Some skaters like a hollow-ground skate and the method shown in
Figs. 3 and 4 can be used for filing a slightly curved surface in
the blade. A piece of tin or sheet metal is shaped over a round
file as shown in Fig. 3. The manner of filing the curves is shown
in Fig. 4. The piece of metal is held over the file and blade of
the skate as the file is worked.

** Lines and Letters Made with a Carpenter's Pencil [306]

The sketch shows some unusual work made with a carpenter's
pencil. If the flat lead is notched with a three-cornered file
(Fig. 1), two parallel lines may be drawn at one stroke, or
various rulings may be made, as shown in Fig. 2. Broad lines can
be made, as shown in Fig. 3, or unequal widths as in Fig. 4.

[Illustration: Pencil Points and Their Work]

In Figs. 2, 5 and 6 are shown lines especially adapted for the
bookkeeper or draftsman. If one lacks the ability to draw old
English letters with a pen, the letters may be first drawn with a
carpenter's pencil (Fig. 7) and the outlines marked with ink and
finally filled in. Narrow lines are made with points cut as in
Figs. 8 and 9. A little practice with the carpenter's pencil in
making these letters will enable the student to finally produce
them with the pen used for the purpose.

** Insulating Aluminum Wire [306]

Aluminum wire plunged hot into a cold solution of carbonate of
soda becomes coated with a strong layer of oxide which forms an
excellent insulator to electricity.

** How to Build an Ice-Yacht [307]
Condensed from an article by H. Percy Ashley in Rudder.

The plans and specifications shown in the illustrations are for
making a 400-ft. class ice-yacht, having a double cockpit to
accommodate four persons. The weight of the persons in the forward
cockpit keeps the boat from rearing when in a stiff breeze. The
forward cockpit can be removed if necessary. The materials used
are: backbone,

[Illustration: Ice-Yacht Complete]

white pine; center, clear spruce; sides, white oak caps; runner
plank, basswood, butternut or oak; cockpit, oak; runners, chocks,
etc., quartered white oak. All the iron work should be first-grade
Swedish iron, with the exception of the runners, which are soft
cast iron.

It is not necessary to go into