long by the booksellers' channels. I shall be very glad, if I do not ask too much, to receive from you in return a copy of your own last volume of observations, your Memorie del Nuovo Osservatorio del C. R, 1852-1855, containing your physical observations of the Sun in reference to distribution of heat, researches with which I desire to be better acquainted.
In writing today I wish to mention to you that I have been very rigorously observing the positions of the Solar spots for the last 4 years, taking every opportunity for the purpose which my climate has afforded and which have not been lost by absences from home, opportunities which have averaged about 225 days a year. My mode of observation* is exactly described in No 5. Vol XIV of the R.A.S. Monthly Notices, and my mode of reduction in No 6. Vol XV, with a detailed specimen of reduction and examples illustration of precision. This method of
*(which requires rather a large flat field and low power)
