A table for reducing the barometric readings at Ben Nevis Observatory to sea-level was given in the former volume of observations, and is reprinted here. The table was compiled by direct comparison of the barometric readings at the Ben Nevis Observatory and at the Public School, Fort-William, and consists of the average difference between these barometers, both being reduced to 32°, and the Fort-William one brought to sea-level, for each tenth of an inch of pressure from 30·9 to 27·4 inches, and for each degree of temperature from 16° to 75°. Any missing values were filled in by interpolation, and the whole smoothed by cross averaging. A full description of the preparation of the table, which is regarded as of a provisional character, will be found in the former volume. (See Transactions Royal Society, Edinburgh, vol. xxxiv. p. xxv.)