In a former paper on this subject, the author gave a selection from his observations on the polarisation of the atmosphere. After its publication, he received a long and elaborate memoir on the same subject by Dr R. Rubenson, containing a series of valuable observations made at Rome on the place of maximum polarisation, and on the intensity of the maximum polarisation at different hours of the day. Important observations on the polarisation of the atmosphere have also been made by M. Liais and M. Andres Poey, and the value of such observations, in determining the height and constitution of our atmosphere, has been universally recognised.