Board of Longitude would approve providing Lieutenant Forbes with apparatus JH suggested. Inappropriate for any member to address Admiralty separately. Payment of expenses to committee members.

Abandons TY's argument on Mr. Roberts's object glass. Asks JH's help in understanding A. J. Fresnel's calculations of diffraction and Josef Fraunhofer's discontinuous functions.

T. M. Brisbane is in town. Can JH meet him? JH's computations of definite integrals are simpler, more direct than P. S. Laplace's and more conclusive than Leonhard Euler's. Comments on W. H. F. Talbot's letters demonstrating Josef Fraunhofer's theorem.