+------+---+---+---+---+---+---+---+---+
|      | A | B | C | D | E | F | G | H |
+------+---+---+---+---+---+---+---+---+
|    1 | *   o   o   *   o   o   o   o |
|    2 | *   o   *   *   o   o   o   o |
|    3 | +   *   *   *   o   o   o   o |
|    4 | +   o   *   *   o   o   o   o |
|    5 | o   +   *   *   *   *   o   o |
|    6 | o   +   *   *   o   *   o   o |
|    7 | o   o   +   *   o   o   o   o |
|    8 | o   o   o   +   *   o   o   o |
|    9 | o   o   o   *   +   o   o   o |
|   10 | o   o   o   o   o   +   o   o |
|   11 | o   o   o   *   o   o   +   * |
|   12 | o   o   *   *   o   +   +   + |
|   13 | o   o   *   o   o   o   o   o |
|   14 | o   o   *   o   o   o   o   o |
|   15 | o   o   +   o   o   o   o   o |
|   16 | o   o   +   +   *   o   o   * |
+--------------------------------------+

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  The front surface is divided into squares of such size that the pegs may be introduced and withdrawn with ease.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.

-------------------------------------------------------

-------
Stewart & Gee 229
Physical Manip. 85    Intensity of Gravity—­Borda’s Method  39
Glazebrook & Shaw 132
------------------------------------------------------------

--

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 ordinary slate nail and a common picture frame nail with a brass head.  The latter indicates work to be done, the former work done.

To prepare the board for service, brass headed nails are placed opposite each experiment, and below the names, care being taken not to have more than one nail in the same horizontal row, unless it is intended that two persons or more are to work upon the same experiment.

There will be no conflict when the brass nails occupy diagonal lines.  If they do not, a glance will show the fact.

After an experiment has been performed and a report made upon the usual blank, the brass nail is removed and a slate nail put in its place.