This department does not, indeed, lie within the original purpose of the Observatory as that was defined in the warrant given to Flamsteed, and yet is so intimately connected with it, through its bearing on navigation, that there can be no question as to its suitability at Greenwich. Indeed, its creation is a striking example of the thorough grasp which Airy had upon the essential principles which should govern the great national observatory of an essentially naval race, and of the keen insight with which he watched the new development of science. The Magnetic Observatory, therefore, the purpose of which was to deal with the observation of the changes in the force and direction of the earth's magnetism--an inquiry which the greater delicacy of modern compasses, and, in more recent times, the use of iron instead of wood in the construction of ships has rendered imperative--was suggested by Airy on the first possible occasion after he entered on his office, and was sanctioned in 1837. The Meteorological Department has a double bearing on the purpose of the Observatory. On the one side, a knowledge of the temperature and pressure of the atmosphere is, as we have already seen, necessary in order to correct astronomical observations for the effect of refraction. On the other hand, meteorology proper, the study of the movements of the atmosphere, the elucidation of the laws which regulate those movements, leading to accurate forecasts of storms, are of the very first necessity for the safety of our shipping. It is true that weather forecasts are not issued from Greenwich Observatory, any more than the _Nautical Almanac_ is now issued from it; but just as the Observatory furnishes the astronomical data upon which the Almanac is based, so also it takes its part in furnishing observations to be used by the Meteorological Office at Westminster for its daily predictions. Those predictions are often made the subject of much cheap ridicule; but, however far short they may fall of the exact and accurate predictions which we would like to have, yet they mark an enormous advance upon the weather-lore of our immediate forefathers. 'He that is weather wise Is seldom other wise,' says the proverb, and the saying is not without a shrewd amount of truth. For perhaps nowhere can we find a more striking combination of imperfect observation and inconsequent deduction than in the saws which form the stock-in-trade of the ordinary would-be weather prophet. How common it is to find men full of the conviction that the weather must change at the co-called 'changes of the moon,' forgetful that 'If we'd no moon at all-- And that may seem strange-- We still should have weather That's subject to change.'