two-hour laboratory periods
and two class periods that usually run into somewhat over one hour
each. These sections are limited to twenty-five, and a smaller number
than this would be desirable. The responsibility for the course rests
naturally upon the individual instructors of these small sections.
These men also share in the demonstration work, since each is usually
an enthusiast in some particular field and will make a great effort in
his own specialty to give a successful popular presentation of the
important ideas involved. The enthusiasm which this plan has
engendered is very great. Attendance is crowded and there is always a
row of visitors, teachers of the vicinity, advanced students in other
fields of work, or undergraduates brought in by members of the class.
These latter especially are encouraged, as this does much to offset
current ideas that physics is a subject of unmitigated severity. The
particular topics put into these demonstrations will be discussed in
paragraphs below, which take up in more detail the organization of the
special subdivisions of the material in a general physics course.

=Mechanics a stumbling block--How to meet the difficulty=

Mechanics is a stumbling block at the outset. As we have indicated
above, it must form the beginning of any course that is analytic in
aim. There is no question of sidestepping the difficulty: it must be
surmounted. A judicious weeding during the first week is the initial
part of the plan. Interest may be aroused at once in the demonstration
lectures by mechanical tricks that show apparent violations of
Newton's Laws. These group around the type of experiment which shows a
modification of the natural uniform rectilinear motion of any object
by some hidden force, most often a concealed magnetic field. The
instinctive adherence of every one to Newton's dynamic definition,
that acceleration defies the ratio of force to inertia, is made
obvious by the amusement with which a trick in apparent defiance of
this principle is greeted. Informality of discussion in such
experiments, questions on the part of the instructor that are more
than rhetorical, and volunteer answers and comment from the class
increase the vividness of the impressions. A mechanical adaptation of
the "monkey on the string" problem, using little electric hoists or
clockworks, introduces interesting discussion of the third law in
conjunction with the second. A toy cannon and target mounted on easil