Reflects on relations between differences of same power of zero. Reviews procedure developed for determining terms and law of coefficients. JH's critique expanded role for these, but HW disagrees with JH's latest comments.

Has procured an actinometer and would like details of the scale.

Would he answer some of his queries when he has leisure? Queries on the law of beats for unison sounds. Met JH's daughter on Monday, who gave a fair account of JH and his recent work.

Has long held the view that a pipe underneath the strings of a piano would increase the resonance. Had not conceived such an instrument as JH suggested. Why are 3rds and 6ths more agreeable to the ear than 4ths and 5ths?

Regrets letter read the night before at the R.A.S. of JH's wish to resign and hopes JH's health allows him to come occasionally and be a nominal member. Discusses Piazzi Smyth's preparations for voyage to Teneriffe.

Sending him a copy of her Familiar Astronomy and inviting his comments on this work. His works are well known in America.

Writes to clarify his understanding of the word 'fluorescence.' Asks JH to review a paper on color-blindness.