Benjamin Franklin's Inventions, Discoveries, and Improvements
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Name: ____________________________________
Benjamin Franklin's Inventions, Discoveries, and
Improvements
Bifocals
A modern replica pair of the type of split bifocal spectacles known to
have been worn by Benjamin Franklin in the mid 1780s
Bifocals are eyeglasses with an upper and lower half, the upper for distance, and the
lower for reading. Bifocals are commonly prescribed to people with presbyopia, a
condition that Franklin suffered. Franklin wrote, in August 1784 to his friend George
Whatley, that he was "happy in the invention of double spectacles, which serving for
distant objects as well as near ones, make my eyes as useful to me as ever they were."
Electricity
Franklin did not, of course, invent electricity, but he discovered many things about it,
previously not understood.
Franklin's Kite Experiment
Before Franklin started his scientific
experimentation, it was thought that electricity
consisted of two opposing forces. Franklin
showed that electricity consisted of a "common
element" which he named "electric fire."
Further, electricity was "fluid" like a liquid. It
passed from one body to another — however it
was never destroyed. In a letter to Peter
Collinson, Franklin wrote that the "fire only
circulates. Hence have arisen some new items
among us. We say B (and other Bodies alike
circumstanced) are electricisedpositively;
A negatively; Or rather B is
electricised plus and A minus ...These
terms we may use till philosophers give us
better."
Franklin's work became the basis for the single fluid theory. When something is being
charged, such as a car battery, electricity flows from a positive body, that with an
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excess charge, to a negative body, that with negative charge. Indeed, a car battery has
plus and minus signs on its terminals.
Franklin wrote Collinson in another letter that: "I feel a Want of Terms here and doubt
much whether I shall be able to make this intelligible." Not only did Franklin have to
posit theories, he also had to create a new language to fit them. Some of the electrical
terms which Franklin coined during his experiments include:
battery conductor positively
charge plus negatively
condensor minus armature
They are still the terms we use today.
Lightning Rod
Rod believed to be an original of Franklin's
Once Franklin had an understanding of
the behavior of electricity, he set about to
protect houses from the destructive forces of
lightning. A lightning rod, simply, is a rod
attached to the top of a building, connected to
the ground through a wire. The electric charge
from lightning strikes the rod and the charge is
conducted harmlessly into the ground. This
protects houses from burning down and people
from electrocution.
Franklin Stove
Franklin's original design for the Franklin stove.
In colonial America, homes were
warmed by a fireplace. The
Franklin stove, invented in 1742,
is a metal-lined fireplace that
stands in the middle of a room. It
has rear baffles for improved
airflow. It provides more heat and
less smoke than an open
fireplace and uses less wood.
This cast-iron furnace would
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radiate heat from the middle of
the room in all directions, and the
iron walls even absorbed heat,
providing warmth o the room long
after the fire went out.
Swim Fins
Benjamin Franklin was an avid swimmer from a very
young age. Throughout his life he consistently
promoted its healthful benefits. At the ripe old age of
11 he invented a pair of swim fins. However, unlike
today's foot flippers, these were attached to one's
hands. His advocacy for swimming was recognized by
his induction into the International Swimming Hall of
Fame in 1968.
Odometer
Franklin was curious as to how far he was traveling by carriage, in his role as
postmaster, for his travels between Philadelphia and Boston.
While the concept of the odometer dates back to ancient times, Franklin did create his
own version. The concept was to attach the device near the wheels of a carriage,
determine the circumference of the wheel and the number of revolutions required to
travel a mile, and have the device register the distance traveled.Name: ____________________________________
Benjamin Franklin, His Inventions, Study Guide
Practice Quiz
1. Ben Franklin created Bifocals, and bifocals are commonly prescribed to people with
what eye condition?
a. Blindness
b. Astigmatism
c. Presbyopia
2. Bifocals are used to see in which two ways?
a. Distant objects as well as near objects
b. Distant objects and double vision
c. Near objects and Peripherals
3. What does the prefix bi mean?
a. Three
b. One
c. Two
4. What did Franklin name the “common element” in electricity?
a. Electric fire
b. Electric energy
c. Electric movement
5. Electricity has what two types of charges?
a. Negative and Negative
b. Positive and Neutral
c. Positive and Negative
6. What were three electrical terms we gained from Franklin?
a. Battery, conductor, condenser
b. Fluid, fire, neutral
c. Engine, caliper, igniteName: ____________________________________
7. What was the purpose of a lightening rod?
a. Gather electricity into energy and power houses
b. Protect house from burning down and electrocuting people
c. Create fires for heating houses and ovens
8. What was the significance of the Franklin Stove?
a. It provided more heat and less smoke.
b. It provided a larger surface for cooking.
c. It could be used by gathering electricity.
9. Where were the Franklin Stoves located in room?
a. By the bathroom
b. In the kitchen
c. In the middle of the room
10. Since Franklin was an avid swimmer, he invented swim fins that were attached where?
a. A swimmer’s thighs
b. A swimmer’s hands
c. A swimmer’s feet
11. Did Franklin make the first odometer?
a. Yes
b. No
12. How did Franklin’s odometer work?
a. It registered speed by using knots tied to a rope and calculating latitude and
longitude.
b. It tracked speed by a clock device connected to a horse’s leg that counted its
steps until reaching a mile.
c. It tracked the circumference of the wheel and the number of revolutions
required to travel a mile.You can also read
