There is an old story about a physics student finding novel ways to measure the height of a building
using a barometer. The story is retold by Alexander Calandra in The Teaching of Elementary Science
and Mathematics. [3]
[3] St. Louis, Washington University, 1961.
A student failed an exam after he refused to parrot back what he had been taught in class. When the
student protested, I was asked to act as arbiter. I went to the professor's office and read the
examination question: "Show how it is possible to determine the height of a tall building with the aid
of a barometer."
The student had answered: "Take the barometer to the top of the building, attach a long rope to it,
lower the barometer to the street and then bring it up, measuring the length of the rope. The length of
the rope is the height of the building."
A high grade is supposed to certify competence in physics, but the answer did not confirm this. I
suggested that the student have another try at answering the question. I gave the student six minutes,
with the warning that his answer should show some knowledge of physics. In the next minute he
dashed off his answer, which read: "Take the barometer to the top of the building and lean over the
edge of the roof. Drop the barometer, timing its fall with a stopwatch. Then, using the formula for the
distance travelled by a falling object, S = 1/2 a t^2 calculate the height of the building." At this point, I
gave the student full credit.
The student went on to propose three other methods of measuring a building's height with a barometer:
Take the barometer out on a sunny day and measure the height of the barometer, the length of its
shadow, and the shadow of the building. By the use of a simple proportion, determine the height of the
building.
Take the barometer and begin to walk up the stairs. As you climb the stairs, mark off the length of the
barometer along the wall. Then count the number of marks, and this will give you the height of the
building in barometer units.
Last (and probably least) offer the barometer as a gift to the building superintendent if he will just tell
you how high the building is.
When this old story was rehashed at Sun as a "science puzzler," 16 more ingenious new methods for
barometric building measurement were suggested! The new responses were of the following types:
The Pressure Method: Measure the air pressure at the bottom and top of the building, then compute
the height of the building from the pressure difference. This is the only method that actually uses the
barometer for its designed purpose of measuring air pressure. Although aircraft altimeters often work
by this principle, it is one of the least accurate methods for measuring a building's height.
The Pendulum Method: Go onto the building's roof, and lower the barometer on a string until it almost
reaches the ground. Swing the barometer and measure the pendulum's period of oscillation. From this
the length of the pendulum, and hence the building, can be calculated.
The Avarice Method: Pawn the barometer to raise seed money for a chain letter campaign. Then stack
the currency thus obtained against the building, measuring it in units of currency thickness. No
comment on how to stay ahead of the police long enough to measure the building.