Mr. Glaisher's instrumental outfit was on an elaborate and costly scale, and the programme of experimental work drawn up for him by the Committee of the British Association did not err on the side of too much modesty. In the first place the temperature and moisture of the atmosphere were to be examined. Observations on mountain sides had determined that thermometers showed a decrease of 1 degree F. for every 300 feet, and the accuracy of this law was particularly to be tested. Also, investigations were to be made as to the distribution of vapour below the clouds, in them, and above them. Then careful observations respecting the dew point were to be undertaken at all accessible heights, and, more particularly, up to those heights where man may be resident or troops may be located. The comparatively new instrument, the aneroid barometer, extremely valuable, if only trustworthy, by reason of its sensibility, portability and safety, was to be tested and compared with the behaviour of a reliable mercurial barometer. Electrical conditions were to be examined; the presence of ozone tested; the vibration of a magnet was again to be resorted to to determine how far the magnetism of the earth might be affected by height. The solar spectrum was to be observed; air was to be collected at different heights for analysis; clouds, also upper currents, were to be reported on. Further observations were to be made on sound, on solar radiation, on the actinic action of the sun, and on atmospheric phenomena in general. All this must be regarded as a large order where only a very limited number of ascents were contemplated, and it may be mentioned that some of the methods of investigation, as, for instance, the use of ozone papers, would now be generally considered obsolete; while the mechanical aspiration of thermometers by a stream of air, which, as we have pointed out, was introduced by Welsh, and which is strongly insisted on at the present day, was considered unnecessary by Mr. Glaisher in the case of wet and dry bulb hygrometers. The entire list of instruments, as minutely described by the talented observer, numbered twenty-two articles, among which were such irreproachable items as a bottle of water and a pair of scissors.