“February 11.—­Used up.  Hypochondrical and bedevilled.”

“Ditto 12.”

“13.—­Not good for much.”

“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.”

[For many years after this his favourite mode of recruiting from the results of a spell of overwork was to take a short walking tour with a friend.  In April 1857 he is off for a week to Cromer; in 1860 he goes with Busk and Hooker for Christmas week to Snowdon; another time he is manoeuvred off by his wife and friends to Switzerland with Tyndall.

In Switzerland he spent his summer holidays both in 1856 and 1857, in the latter year examining the glaciers with Tyndall scientifically, as well as seeking pleasure by the ascent of Mont Blanc.  As fruits of this excursion were published late in the same year, his “Letter to Mr. Tyndall on the Structure of Glacier Ice” ("Phil.  Mag.” 14 1857), and the paper in the “Philosophical Transactions of the Royal Society,” which appeared—­much against his will—­in the joint names of himself and Tyndall.  Of these he wrote in 1893 in answer to an inquiry on the subject:—­]

By the Observations on Glaciers I imagine you refer to a short paper published in “Phil.  Mag.” that embodied results of a little bit of work of my own.  The Glacier paper in the “Phil.  Trans.” is essentially and in all respects Professor Tyndall’s.  He took up glacier work in consequence of a conversation at my table, and we went out to Switzerland together, and of course talked over the matter a good deal.  However, except for my friend’s insistence, I should not have allowed my name to appear as joint author, and I doubt whether I ought to have yielded.  But he is a masterful man and over-generous.

[And in a letter to Hooker he writes:—­]