"21.--Toothache, incapable all day."

[And again:--]

"March 30. Voiceless."

"31.--Missed lecture."

[And]

"April 1.--Unable to go out."

[He would come in thoroughly used up after lecturing twice on the same
day, as frequently happened, and lie wearily on one sofa; while his
wife, whose health was wretched, matched him on the other. Yet he would
go down to a lecture feeling utterly unable to deliver it, and, once
started, would carry it through successfully--at what cost of nervous
energy was known only to those two at home.

But there was another branch of work, that for the Geological Survey,
which occasionally took him out of London, and the open-air occupation
and tramping from place to place did him no little good. Thus, through
the greater part of September and October 1856 he ranged the coasts of
the Bristol Channel from Weston to Clovelly, and from Tenby to Swansea,
preparing a "Report on the Recent Changes of Level in the Bristol
Channel."] "You can't think," [he writes from Braunton on October 3,]
"how well I am, so long as I walk eight or ten miles a day and don't
work too much, but I find fifteen or sixteen miles my limit for
comfort."