A, B, C, etc., are cards upon which are the names of students. 1,
2, 3, etc., are cards like the one described in the article. The
small circles (o) represent unassigned experiments. The black
circles (*) (slate nails) represent work done. The caudate circles
(+) (brass nail) represent work assigned.

The indicator consists of a plank of any convenient length and breadth.
The front surface is divided into squares of such size that the pegs may
be introduced and withdrawn with ease. At each corner of the squares
holes are bored into which nails may be placed. There is a blank border
at the top and another on the left side. At the top of each vertical
column of holes is placed a card holder. This is made of light tin
turned up on the long edges--which are vertical--and tacked to the
board. Opposite each horizontal row of holes is a similar tin card
holder, but of greater length, and having its length horizontal. The
holders at the top of the board contain cards upon which the names of
the class are written.

Cards, like the following, are prepared for the horizontal holders.

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Stewart & Gee 229
Physical Manip. 85 Intensity of Gravity--Borda's Method 39
Glazebrook & Shaw 132
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These cards are numbered from one to any desired number and are arranged
in the holders consecutively.

Two kinds of nails are provided to fit the holes in the board: An