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98
Saturday Oct 28th 1843
My attention had particularly drawn to the subject of the last page from having seen last night, the letter of Dr Faraday to the Secretary of the East India House, on the question of defending the powder houses of India from thunder -. The Dr does not think that there is any danger from the induction of a rod near the house, but he appears to have no idea of the induction produced by a conductor at the the moment it is connecting a discharge, which I have discovered. [See page 65 of this vol.]
The effects I have described as witnessed in the case of Pres Hamiltons House, are of this kind, and yesterday I found in the Comptes Rendus for Aug 9th 1843, an account of the steeple of the Strasbourgh cathedral being struck, and at the moment of the flash, every part of the shop of a tin man situated near the foot of the rod, or rather where the rod entered a fish well, was illuminated by spark of electricity, athough no thunder was heard.
[[drawing]] In the paper of Dr Faraday (for an abstract of which, see common place book), an account is given of some experiments on lateral discharge one of which consists in throwing sparks on a thick wire C W [[refers to drawing]], aside of which a wire is placed 10 or 12 feet long an induced or rather lateral spark is seen at [[underlined]] a [[/underlined]] and [[underlined]] b [[/underlined]], and this is a fine illustration of the fact that I have been contending, for that one part of the wire is + (plus) to the other.
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99
[[Note in left margin]] Conjecture proved true pg 158 [[/End note]]
The nature of the sparks at [[underlined]] a [[/underlined]] and [[underlined]] b [[/underlined]] in the experiment of the bottom of the last page, ought to be examined, is is probably a double one.
There is also some objection to the experiment, as giving a double result, since the primary current would produce in the lateral wire as it is placed in the figure, an induced current, or rather two induced currents.
[[Note in left margin]] Needles No 10 [[/End Note]]
[[Note in right margin]] Magnetization of needles by the battery discharge [[/End Note]]Battery charged to 48˚
Needles distance defl
1 1/8 34
2 1/4 31
3 3/8 27
4 1/2 25
5 5/8 24
6 6/8 21
7 7/8 22
8 1 23
9 1 1/8 24
10 1 1/4 23
11 1 3/8 23
12 1 1/2 22
13 1 5/8 20
14 1 3/4 22˚
[[Right margin note]] NB in the case of a needle placed on the ribband in an other exp of same charge the def was 36. [[/End note]]
In this experiment, instead of a single wire the discharge was passed through a copper ribbon 1 1/2 of an inch in width, and 2 feet long.
[[Left margin note]] 1/2 Needles No 10 [[/End Note]]
Needles Dist. defl.
Middle 1 on 23 [[bracket to the right of this line and the next]] 21 1/2 [[/End bracket]]
Middle 2 " 20 [[bracket to the right of this line and the next 3 lines]] 21 3/4 [[/End bracket]]
N Side 3 " 22
N Side 4 " 22
S Side 5 " 23
S Side 6 " 20
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Transcription Notes:
Comptes rendus - French scientific journal
