Provides sources of information about polarization, spectroscopy and solar physics for son John, who is continuing his preparation for observing the solar eclipse [see JH's 1867-9-12].
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Provides sources of information about polarization, spectroscopy and solar physics for son John, who is continuing his preparation for observing the solar eclipse [see JH's 1867-9-12].
The R.S.L. proposes sending telescopic and spectroscopic equipment to India to observe the solar eclipse of 1868. They want to know if son John would be prepared to make the observations. John could use some of his leave time in England to prepare.
Writes to son John [who is now in England] further about the solar eclipse observations [see JH's 1867-5-18]; comments on family matters, and talks about making improvements in photographic processes, so that JH is able to print on both sides of the paper.
Has been observing sunspots and talks about sunspot cycles; JH is glad to see that son John has been practicing observing with the spectroscope in preparation for the Indian solar eclipse [see JH's 1867-6-12].