Letter to George F. Fitzgerald from Sir Oliver Lodge
Title
Letter to George F. Fitzgerald from Sir Oliver Lodge
Creator
Date
Identifier
GFF 2/53
Description
Handwritten letter from Sir Oliver Lodge, 2 Grove Park, Liverpool, to George F. Fitzgerald, dated 28 April 1895. Lodge discusses an experiment involving a magnetic circuit, iron and copper. 2pp.
Transcription:
"M d Φ
Thanks for letter. I agree with all you say, and I had used many of the arguments myself, but I had not realised that no [cloud?] circuit experience could be crucial. At the same time some of them are surprising (see over). The motion of this one was that or the orthodox rotary field view when the magnet had no keeper the extend line would cut the [?] wires; whereas when the magnetic circuit is complete, they won't (I know it's lost as an argument but it's plausible) (the fact is that the keeper slightly increases the current, as you suppose). As to the keeper rotating between the poles of a magnet, the current is 40 or 50 times stronger with iron than with copper. which I don't think would have been primarily expected, although is recommended.
But now here is a curious experiment. A is a rotating iron drum, B is a cylindrical keeper forming an electromagnet with air gap annular between A and B. Wire, [r?] with A, passes through hole in it and cuts lines of force in ring (once apparent). Will there be a current topped off? (Could you not return with me on 4th and stay Sunday. We have a debating soc [?] to diverge on 4th on differences in Social Corporation.) Answer, no, because the wire in hole in iron is not really screened but feels the lines flashy across hole as the iron turns and cuts just as many as the other 1/2 of the loop does. Or if that's not right, what is? Lines never more at all?
Preliminary mechanics question will reach you with this. Honours Physics in 2 batches have already been sent.
(Very sorry you are not coming here on 4th. Give us some time if it's possible. Yours OJL)"
Transcription:
"M d Φ
Thanks for letter. I agree with all you say, and I had used many of the arguments myself, but I had not realised that no [cloud?] circuit experience could be crucial. At the same time some of them are surprising (see over). The motion of this one was that or the orthodox rotary field view when the magnet had no keeper the extend line would cut the [?] wires; whereas when the magnetic circuit is complete, they won't (I know it's lost as an argument but it's plausible) (the fact is that the keeper slightly increases the current, as you suppose). As to the keeper rotating between the poles of a magnet, the current is 40 or 50 times stronger with iron than with copper. which I don't think would have been primarily expected, although is recommended.
But now here is a curious experiment. A is a rotating iron drum, B is a cylindrical keeper forming an electromagnet with air gap annular between A and B. Wire, [r?] with A, passes through hole in it and cuts lines of force in ring (once apparent). Will there be a current topped off? (Could you not return with me on 4th and stay Sunday. We have a debating soc [?] to diverge on 4th on differences in Social Corporation.) Answer, no, because the wire in hole in iron is not really screened but feels the lines flashy across hole as the iron turns and cuts just as many as the other 1/2 of the loop does. Or if that's not right, what is? Lines never more at all?
Preliminary mechanics question will reach you with this. Honours Physics in 2 batches have already been sent.
(Very sorry you are not coming here on 4th. Give us some time if it's possible. Yours OJL)"
Source
RDS Library & Archives GFF collection of letters
Rights
Copyright RDS Library & Archives. Publication, transmission or display is prohibited without formal written approval of the RDS Library & Archives.
Relation
RDS Science Archive
Format
Manuscript
Language
English
Type
Coverage
1870-1901
Collection
Citation
Lodge, Oliver, Sir, 1851-1940, “Letter to George F. Fitzgerald from Sir Oliver Lodge,” RDS Digital Archive, accessed July 11, 2025, https://digitalarchive.rds.ie/items/show/1312.