Google Books (via Google search, tbm=bks, in Chrome), 2026-10-08
Queries
"magnetic storm" "July 16" 1892 Boston "milli-amperes" (no exact match; Google relaxed quotes)
"storm of July 16, 1892" telegraph "New York" Providence (relaxed)
"magnetic storm of unexampled severity" 1892
Result pages read with get_page_text. Book pages themselves not opened (result links blocked from scripted reading by the extension's query-string filter); snippets only.
Found [web: Google Books snippets]
The Electrical Engineer (New York weekly), vol. 14, 1892, p.79: article "... STORM OF JULY 16, 1892. BY [name garbled in snippet: 'Wohin I.']": "A MAGNETIC storm of unexampled severity and duration swept over the United States on Saturday, July 16, almost completly paralyzing the entire telegraphic service of the country for several hours. The writer had ..."; another snippet on the same page: "... Boston wire in which the current showed incessant variations both in ... milliamperes. Suddenly at 12:20 p.m. a tremendous wave struck the wire ...".
Electricity: A Popular Electrical Journal, vols. 4-5, 1893, p.157: "... Boston, during the magnetic storm of July 16, 1892, which showed that the abnormal current in the wire reached the strength of 133 milliamperes, and the maximum difference of potential of the earth at New York and Boston was 492 ...".
Terrestrial Magnetism and Atmospheric Electricity, 1904, p.24 (also indexed under JGR vols. 10-12): "... July 16, 1892, a disturbance was noted, and the line from New York to Providence ... storm the East-West lines were especially disturbed ...".
Bearing on the claims
Claim 2 (earth currents in telegraph wires): the book's p.134 table ("RECORD OF MAGNETIC STORM OF JULY 16, 1882", New York-Boston peak 133 mA in the text; New York-Providence 280 mA at 644 V) matches measurements published in 1892-1893 for the storm of 16 July 1892 (133 mA; 492 V New York-Boston). So the table is not Larkin's own measurement: it matches the 1892-93 trade press on the 1892 storm; direction of copying unknown [corrected 2026-10-09 after QE: was "copied from an electrical-trade source"], and the year was misprinted (or mistaken) in the book. This gives the reviewers an independent primary record of the earth-current values, and a date that lines up with Larkin's own sunspot and aurora observations of 9-16 July 1892 (Science letter, research/2026-10-08-internet-archive.md).
492 V / 133 mA = 3,700 ohms, the figure the deep read inferred from the book's volts column; so the book's stated "2,700 ohms" disagrees with the source's own numbers.
Not reached / next
Full text of Electrical Engineer vol. 14 p.79 (author's name, full tables): look on HathiTrust full view or Google Books full view; not on archive.org by title search.