The difficulties attending the management of a physical laboratory are
much greater than those of a chemical one. The cause of this lies in the
fact that in the latter the apparatus is less complicated and the pieces
less varied. Any contrivance that will reduce the labor and worry
connected with the running of a laboratory is valuable.
A physical laboratory may be arranged in several ways. The apparatus may
be kept in a store room and such as is needed may be given to the
student each day and removed after the experiments are performed; or the
apparatus for each experiment or system of experiments may be kept in a
fixed place in the laboratory ready for assembling; for certain
experiments the apparatus may be kept in a fixed place in the laboratory
and permanently arranged for service.
Each student may have his own desk and apparatus or he may be required
to pass from desk to desk. The latter method is preferable.
When a store room is used the services of a man are required to
distribute and afterward to collect. If the apparatus is permanently
distributed, a large room is necessary, but the labor of collecting and
distributing is done away with.
There are certain general experiments intended to show the use of
measuring instruments which all students must perform. To illustrate the
use of the indicator I have selected an elementary class, although the
instrument is equally applicable to all classes of experiments.
Having selected a suitable room, tables may be placed against the walls
between the windows and at other convenient places. Shallow closets are
built upon these tables against the wall; they have glass doors and are
fitted with shelves properly spaced. A large number of light wooden
boxes are prepared, numbered from one up to the limit of the storage
capacity of the closets. A number corresponding to that upon the box is
placed upon the shelf, so that each one after removal may be returned to
its proper place without difficulty. On the front of the box is a label
upon which is written the experiment to be performed or the name of the
apparatus whose use is to be learned, references to various books, which
may be found in the laboratory library, and the apparatus necessary for
the experiment, which ought to be found in the box. If any parts of the
apparatus are too large to be placed in the box, the label indicates by
a number where it may be found in the storage case.
It is evident that, instead of the above arrangement, all the boxes can
be stacked in piles in a general store room. The described arrangement
is preferable, as it prevents confusion in collecting and distributing
apparatus when the class is large.
_The Indicator_ (see figure).--Some device is evidently desirable to
direct the work of a laboratory with the least trouble and friction
possible. I have found that the old fashioned "peg board," formerly used
in schools to record the demerits of scholars, modified as in the
following description, leaves nothing to be desired.
The requirements of such an instrument are these: It must show the names
of the members of the class; it must contain a full list of the
experiments to be performed; it must refer the student to the book and
page where information in reference to the experiments or apparatus may
be found; it must show what experiments are to be performed by each
student at a given time; it must give information as to the place in the
laboratory where the apparatus is deposited; it must show to the
instructor what experiments have been performed by each student; it must
prevent the assignment of the same experiment to two students; it must
enable the instructor to assign the same experiment to two or more
students; it must form a complete record of what has been done, what
work is incomplete, and what experiments have not yet been assigned; it
must also be so arranged that new experiments or sets of experiments may
be exhibited.
+------+---+---+---+---+---+---+---+---+
| | 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.
The board will show by the slate nails what work has been done by each
student, by the brass nails what is yet to be done, and by the empty
holes, experiments which have been omitted or are yet to be assigned. A
slate nail opposite an experiment card indicates that that experiment
may now be assigned to another person.
It is evident that the schedule for a whole term may be arranged in a
few minutes and that the daily changes require very little time.
The board is hung in a convenient place. The student as he enters the
laboratory looks for his name on the upper cards and under it for the
first brass nail in the vertical column: to the left he finds the
experiment card. On the left hand end of the slip he sees the book
references, on the right hand end a number--39 in the sample card given
above. Knowing the number, he proceeds to a desk and finds a box
numbered in the same manner. He removes the box from the closet. On the
label of the box is a list of all the apparatus necessary, which he will
find in the box; the label also contains the book references. He
performs the experiment, fills up a blank which he gives to the
instructor, puts all the materials back in the box, replaces the box in
its proper place in the closet and proceeds with the next experiment.
With this indicator there is no difficulty in managing fifty students or
more.
Comparatively little apparatus need be duplicated. Where apparatus is
fixed against a wall a number may be tacked upon the wall and a card
containing the information desired. The procedure is then the same as
with the boxes. The cards on the board being removable, other ones may
be inserted containing information in reference to other boxes having
the same number but containing different materials. There can be no
successful tampering with the board, for the record of experiments
performed is upon the blanks which the students turn in and also in the
individual note books which are written up and given to the instructor
for daily examination.
Lafayette College. J.W. MOORE.
* * * * *