Wilcke,
5 [23] was born on September 6, 1732 in Wismar, Swedish Pommerania,
where his father, Samuel Wilcke, was a priest. His mother was Anna Scheele, a
distant relative to Carl Wilhelm—she was a half second cousin to Carl Wilhelm’s
father. In 1739, his father was appointed vicar in the German Church in Stockholm,
and Johan Carl attended the German School. In 1750, he enrolled at Uppsala
University, where he was supposed to study theology, but devoted his time to
mathematics and physics—i.e. just like Bergman would do a few years later. His
principle teachers were Klingenstierna and Strömer. In 1751, he moved to Rostock,
where his father had friends: as young, Samuel Wilcke had been private teacher to
Angelius Iohannes Aepinus, who since had become professor in rhetoric. Wilcke
also befriended Aepinus brother, natural scientist Franz Ulrich Theodorius Aepinus
(1724–1802). In 1753, he continued his studies in Göttingen and in 1755 he moved
to Berlin, where he lived in the same house as Franz Aepinus and befriended the
famous mathematician Leonard Euler (1707–1783). Wilcke presented his inaugural
thesis [24] in Rostock in October 1757, a thesis concerning electrical experiments.
He returned to Uppsala soon after in order to become docent. Unfortunately, there
was only one professorship in physics in Uppsala, and with a young professor—
Samuel Duræus (1718–1798)—recently appointed, he could not hope for a professorship. Another possibility would however arise. In 1727, Samuel Tham had
donated money to Collegium illustre, a society which had been established by the
House of Nobility (Riddarhuset) in 1625. The money was later transferred to the
Royal Swedish Academy of Sciences and its secretary, Wargentin (Sect. 6.2),
suggested that money from the fund should be used to appoint a Thamian lecturer,
who would serve as vice secretary in the Academy and who would give lectures on
experimental physics. The Academy turned to Klingenstierna for advice, and
Klingenstierna recommended Wilcke, who was appointed in 1759. Wilcke was an
active researcher publishing numerous papers in the Transactions of the Royal
Academy of Sciences. The papers published during the period 1758–1772 mainly
concerns electricity and magnetism, where after his interest shifted to heat. When
Wargentin died in 1784, Wilcke succeeded him as secretary in the Academy.
When Bergman started to study electrical phenomena in the early 1760s, Wilcke
was the main authority on electricity in Sweden. It does not seem like Wilcke and
Bergman knew each other in Uppsala, but Bergman wrote to Wilcke in Stockholm
in spring 1763, asking Wilcke to become his correspondent. Wilcke accepted the
invitation.
In 1762, Bergman published a paper on the electrical properties of calcite
(Iceland spar) [25]. Benjamin Wilson had found that calcite crystals would only be
electrically charged on rubbing at low temperature, and he therefore asked Bergman
to test this in Sweden, as the temperatures in Uppsala typically are much lower than
in London in the winter. Bergman only noted weak charge at −3 °C. He expected
this charge to disappear on heating, but, to his surprice, he found that the charge
increased. Ten crystals displayed the same effect.
6
5
There are no contemporary portraits of Wilcke, except a silhouette.
6
I have found no reliable source referring to any pyroelectric properties of calcite.
5.2 Bergman’s Research on Electricity
63
5 [23] was born on September 6, 1732 in Wismar, Swedish Pommerania,
where his father, Samuel Wilcke, was a priest. His mother was Anna Scheele, a
distant relative to Carl Wilhelm—she was a half second cousin to Carl Wilhelm’s
father. In 1739, his father was appointed vicar in the German Church in Stockholm,
and Johan Carl attended the German School. In 1750, he enrolled at Uppsala
University, where he was supposed to study theology, but devoted his time to
mathematics and physics—i.e. just like Bergman would do a few years later. His
principle teachers were Klingenstierna and Strömer. In 1751, he moved to Rostock,
where his father had friends: as young, Samuel Wilcke had been private teacher to
Angelius Iohannes Aepinus, who since had become professor in rhetoric. Wilcke
also befriended Aepinus brother, natural scientist Franz Ulrich Theodorius Aepinus
(1724–1802). In 1753, he continued his studies in Göttingen and in 1755 he moved
to Berlin, where he lived in the same house as Franz Aepinus and befriended the
famous mathematician Leonard Euler (1707–1783). Wilcke presented his inaugural
thesis [24] in Rostock in October 1757, a thesis concerning electrical experiments.
He returned to Uppsala soon after in order to become docent. Unfortunately, there
was only one professorship in physics in Uppsala, and with a young professor—
Samuel Duræus (1718–1798)—recently appointed, he could not hope for a professorship. Another possibility would however arise. In 1727, Samuel Tham had
donated money to Collegium illustre, a society which had been established by the
House of Nobility (Riddarhuset) in 1625. The money was later transferred to the
Royal Swedish Academy of Sciences and its secretary, Wargentin (Sect. 6.2),
suggested that money from the fund should be used to appoint a Thamian lecturer,
who would serve as vice secretary in the Academy and who would give lectures on
experimental physics. The Academy turned to Klingenstierna for advice, and
Klingenstierna recommended Wilcke, who was appointed in 1759. Wilcke was an
active researcher publishing numerous papers in the Transactions of the Royal
Academy of Sciences. The papers published during the period 1758–1772 mainly
concerns electricity and magnetism, where after his interest shifted to heat. When
Wargentin died in 1784, Wilcke succeeded him as secretary in the Academy.
When Bergman started to study electrical phenomena in the early 1760s, Wilcke
was the main authority on electricity in Sweden. It does not seem like Wilcke and
Bergman knew each other in Uppsala, but Bergman wrote to Wilcke in Stockholm
in spring 1763, asking Wilcke to become his correspondent. Wilcke accepted the
invitation.
In 1762, Bergman published a paper on the electrical properties of calcite
(Iceland spar) [25]. Benjamin Wilson had found that calcite crystals would only be
electrically charged on rubbing at low temperature, and he therefore asked Bergman
to test this in Sweden, as the temperatures in Uppsala typically are much lower than
in London in the winter. Bergman only noted weak charge at −3 °C. He expected
this charge to disappear on heating, but, to his surprice, he found that the charge
increased. Ten crystals displayed the same effect.
6
5
There are no contemporary portraits of Wilcke, except a silhouette.
6
I have found no reliable source referring to any pyroelectric properties of calcite.
5.2 Bergman’s Research on Electricity
63