Sherrington fancies that he saw Helmholtz once on 'the Liverpool landing stage' with Hugo Kronecker. As Helmholtz died in 1894, this would have had to have occurred before Sherrington was appointed Holt Professor of Physiology at the University of Liverpool (1895). One possibility is that the sighting occurred in 1893, when Helmholtz travelled to the United States as head of a German delegation to the Columbian Worlds Exposition in Chicago, described by Cahan.

Though Cahan does not mention Kronecker as a member of a German delegation, he is listed as present on the passenger list for a voyage of the Saale which arrived in the United States on 8th August 1893. Cahan claims that Helmholtz departed for the United States on the Lahn on 8th August 1893 (relying on Koenigsberger, 1903), and that he returned to Germany on the Saale on the 6th October 1893 (relying on correspondence in Seimens-Helmholtz, 1923).

The passenger listings - available at the US national archives (http://www.archives.gov/) - cite the Saale voyage arriving on the 8th of August as from Germany to the United States, departing from Bremen, and travelling via Southampton. The Lahn is listed as arriving in the United States from Bremen on the 17th August 1893, and travelling the same route. Either ship may have passed through Liverpool as well.

Although Helmholtz does not appear to be present on the passenger lists for either ship, a 33-year-old 'engineer', O. Lummer  is listed as 'returning to his country of origin' on a passage of the Lahn arriving in the US from Bremen on 17th August 1893, as is a 37-year-old 'D. Feufsner',  a 35-year-old 'Dr Kurlbann', a 29-year-old 'Sebastian Linback', and a 35-year-old 'A. Prinzharn'.

Cahan cites as accompanying Helmholtz the physicist Otto Lummer, who would have been 33 in 1893 , along with; a 37-38-year-old Karl (rather than 'D.') Feussner; 35-36-year old Ferdinand Kurlbaum (not 'Kurlbann'); a 28-29-year-old Stephan (not 'Sebastian') Lindeck (not 'Linback'); and a 34-35-year-old Ernst (not 'A.') Pringsheim (not 'Pinzharn').

Given that the delegation travelled together, it seems certain then that Helmholtz was on the voyage of the Lahn to the United States, as claimed by Cahan and Koenigsberger, rather than that of the Saale. Sherrington may well have seen Kronecker on the landing stage on his way to the United States. If he did so however, it seems unlikely that Helmholtz was with him.

If Sherrington did see Helmholtz and Kronecker together in 1893, then it would have had to have been on the return voyage. However, as Cahan notes, Helmholtz suffered a fall a few days after leaving for Germany, seriously injuring his head. Even if Kronecker was on the same voyage as Helmholtz, the likelihood that Sherrington saw Kronecker accompany an eldererly and injured Helmholtz taking the opportunity to walk on land whilst the Saale was docked at Liverpool seems slim.

The above evidence does not of course rule out the possibility that Sherrington saw Helmholtz and Kroenecker together in Liverpool prior to this date.