From:
Sir John Herschel
To:
John Herschel (son)
Date:
[12 September 1867]
Source of text:
JHS 6.52
Summary:
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].
Contributor:
John Herschel Project