This note is about 1000 words in length. We have been taught that this much information is contained in a single picture. But, Fig. 1 is so rich that four separate ideas can be obtained from it! The figure appears in The Boy’s Playbook of Science by John Henry Pepper. Pepper tells us that this shows an “assistant standing on the insulating stool and touching the disk of the electroscope while being struck with a dry handkerchief.”

1.
John
Henry
Pepper,
The Boy’s Playbook of Science
(
George Routledge and Sons
,
London
,
1875
), p.
180
.
2.
Thomas B.
Greenslade
 Jr.
, “
Diffraction by a cat’s whisker
,”
Phys. Teach.
38
,
422
(
2000
).
3.
A.
Ganot
,
Elementary Treatise on Physics
, translated and edited by
E.
Atkinson
(
William Wood
,
New York
,
1883
), p.
699
.
4.
Thomas B.
Greenslade
 Jr.
and
Richard H.
Howe
, “
A modern use of Volta’s electroscope
,”
Phys. Teach.
19
,
614
615
(
Dec.
1981
).
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