Account of pendulum experiments undertaken in the Harton Colliery, for the purpose of determining the mean density of the earth, by G. B. Airy

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                                Section III. General<s>y</s> System of observing the
Pendulums and reducing the observations.

<s>31</s>29. <s>La</s> Before describing the observations &c, I will
remark that the pendulums above and below were
mounted in exactly the same manner. Each angle
of the iron stand, in each station, rested on a
single brick: and great care was taken by Mr. Dunkin
that the bearing of these bricks should be perfectly solid.
It was also a subject of Mr. Dunkin's special
attention to make the supplementary hexagonal
iron frame (<s>to</s> which I have described in article
15) quite firm; and, above all, to fix firmly
at the beginning of each series and to examine
carefully at the end of each series the frame carrying
the agate planes. In every instance there were
found perfectly <s>[?]</s> firm in their <s>[?]</s> attachment.
At every interchange of pendulums Mr. Dunkin carefully oiled and wiped the knife-
edges and their agate planes. At the beginning of every Swing, the observer raised the knife-edge
from contact <s>by</s> with the agate plane, <s>[?]</s> by the screw lifting apparatus, and then carried it gently to a
definite line of bearing.
<s>32</s>30. The pendulum being observed in Kater's manner,
by <s>[?]</s> using the concealment of the bright disk on the
clock-pendulum-bob behind the tail of the
detached pendulum, when passing the aperture through
                            
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Manuscript details

Author
George Biddell Airy
Reference
PT/54/5
Series
PT
Date
1855
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Account of pendulum experiments undertaken in the Harton Colliery, for the purpose of determining the mean density of the earth, by G. B. Airy, 1855. From The Royal Society, PT/54/5

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