Encloses copy of JH's essay entitled The Yard, the Pendulum, & the Metre... (1863). Speculates on causes for deviation in pendulum measurements. Recommends using torsion gravimeters in 'proposed operation.'
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Encloses copy of JH's essay entitled The Yard, the Pendulum, & the Metre... (1863). Speculates on causes for deviation in pendulum measurements. Recommends using torsion gravimeters in 'proposed operation.'
If enclosed item is accepted for publication in Photographic News, JH wants to inspect its press, especially 'as respects the Cipher,' and to receive 25 copies.
Reports on G. B. Airy's analysis [R.S.P.T., 153,. 617-] of 177 magnetic storms.
Asks that consideration be given to 'wishes of the Cadet' in selecting a regiment for him.
In response to the gift of a book, JH comments on the philosophy of knowledge, and goes on to say that JH agrees with [John Stuart ?] Mill's rejection of the syllogism as a means of argument. In the postscript, JH comments on the nature of heat.
About geodesic books and JH's encouragement to John to keep asking questions; indeed JH is almost insistent on son John's writing to JH with questions, book needs, and confidences. JH also talks about finding the arithmetical mean of a number of observations. [Also included is the 1st page of a letter to John from one of his sisters.]