Continues to explain matters in perturbation theory. Stresses need for careful observations in solar eclipses. Doubts the existence of the hypothetical intermercurial planet Vulcan.

Thanks for work on diamagnetism and magne-crystallic action [Researches on Diamagnetism (1870)], which JH is excited to read. Mentions long-abandoned plans for magnetization experiments. Envies those who can see JT's 'magic' experiments at Royal Institution.

Cannot attend Eclipse Committee meeting but suggests that an observer carefully look for planets interior to Mercury's orbit, which would, if existing, reach conjunction during total solar eclipses.

Of toads in rocks and stones, and martins in blocks of ice under rivers.

Writes about JH's health; justifies writing by sending some curves prepared by JH's son Alexander.

Sends diagrams showing three new couplets of sunspots. The sun is entering a new phase of activity. Sends drawings made with a glass pen by his son Alexander.