Paper, 'On the computation of the harmonic components of a series representing a phenomenon recurring in daily and yearly periods' by R [Richard] Strachey Strachey writes: 'Following the notation commonly used, the general expression for the harmonic components of the successive terms of a series representing a periodically recurring phenomenon, observed at equal intervals of time, is— an = p0 + P1 cos nz+ q1 sin nz + p2 cos 2 nz+ q2 sin 2nz + &c., where an is the observed value of any term in question; z is the angular equivalent of the time interval between the observations.' Annotations in pencil and ink throughout. Includes six separate computational tables. Subject: Mathematics Received 15 April 1886. Read 13 May 1886. A version of this paper was published in volume 42 of the Proceedings of the Royal Society as 'On the computation of the harmonic components of a series representing a phenomenon recurring in daily and yearly periods'. 1886