The Earliest Electromagnetic InstrumentsChipman, Robert A.
History
The Earliest Electromagnetic Instruments
Chipman, Robert A.
Electric apparatus and appliances
"This magnetic condenser can be a great boon to electro-chemistry," said
Erman, for "it avoids all the difficulties of electric condensers." He
noted that, using the condenser, Poggendorf had already established the
electric series for a great number of bodies, discovered various
anomalies about conductivities, and found a way of detecting dissymmetry
of the poles of a compass needle. On the other hand, even with the
condenser, no magnetic effects have so far been obtainable from a strong
tourmaline, or from a 12,000-pair, Zamboni dry cell.
Poggendorf's own account of his work finally appeared as a very long
article in the journal known as "Oken's Isis."[28] The editorial
controversies mentioned earlier may have occasioned this use of a
periodical of such minor status in the fields of physics and chemistry.
The source of Poggendorf's vision of the multiplier principle was a
little different from Schweigger's inspiration. Aiming at some detailed
analysis of Oersted's observation, Poggendorf ran the connecting wire of
his cell-circuit along a vertical line to just above or below the
pivot-point of the compass needle, then, after a right-angle bend,
horizontally above or below one of the poles of the needle. As he
studied the deflections produced for all four possible positions of such
a wire, with both cell polarities, he came to realize that if a
rectangular wire loop in a vertical plane enclosed a compass needle, all
parts of the horizontal sides of the loop would produce additive
deflections. By a separate experiment, he showed that the vertical sides
of the loop would also increase the deflections. He saw at the same time
that the effect of additional turns would be cumulative.
The multiple surrounding of the needle by a silk-covered wire, in a
plane perpendicular to the long axis of the needle, affords the
physicist a very simple and sensitive means of detecting the
slightest trace of galvanism, or of magnetism produced by it, so
that I have given the name of magnetic condenser to this
construction, though I attach no special value to this name ...
In analyzing the astonishingly increased power which the condenser
gives to the magnetic effect of a circuit, the first question that
arises is how the effect varies with the number of turns, whether it
increases indefinitely or reaches a maximum beyond which additional
turns have no effect. The answer to this first question is linked to
the solution of another, viz, whether the degrees deflection are a
direct expression of the measure of the magnetic force or not.
Public-domain text, read in full here on John Shaqi.
Reviews
Reviews
No reviews yet
Be the first to share your thoughts on this work.
Join the Discussion
Join the discussion
Sign in to leave a comment or review.
Sign InorCreate an account