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methods, tp cause rain, but from America, Europe, India, and Australia come records of their failure, and only personal experience seems to satisfy every nation and each generation of their futility. The chief arguments used in favour of the experiments, besides those alluded to before, were that rain generally followed great battles, explosions, and disturbances of the air as by reverberations of thunder —nay, even the passage of a train through a moisture-laden atmosphere. I was informed that in parts of Wales where slate-quarrying is carried on it usually rains every day while blasting i 3 done, but that the Sundays will be fine because operations cease. Eeviews of troops and sham fights have been followed by rain, and this has been attributed to the firing. The coincidence of rain with reviews has often been unduly impressed upon the minds of people by its effect on smart dresses and uniforms, for the display of which, and for convenience in marching, cumbersome overcoats have been discarded; and this fact discounts such evidence. Professor T. Eussell, in his " Meteorology," says, " It has been supposed that the concussion of artillery-fire in battles produces rain, and that great battles are followed by heavy rain. There is no reason why this should be so. No physical relation has ever been traced between concussion of air and formation of water-drops. The belief is very ancient that battles are followed by rain. In Plutarch's Lives it is related that after the battle of Marsalia in France, a great rainfall followed, and it is mentioned as being a well-known fact that all great battles are followed by heavy rain, This was certainly a case when rain was not due to artillery-fire." Eain, if coincident with battles, has the most marked effects on these stupendous operations of human activity. Globules of water are formed on particles of dust, and the vapour-atoms of gases, or ions; but there is no reason to suppose that these droplets are hollow vesicles which could be burst by explosions. Condensation is induced in a supersaturated atmosphere by the presence of dust, the fumes of ammonia, phosphorus, sulphur, Sec., as these particles form nuclei for the minute spherical drops of water. The passage of a train might bring such in smoke, but the results would only be insignificant. Fog and smoke may hang over London, but the rain is no greater than in the country. Thunder and lightning are, again, effects of electrical disturbance, which is also a result of the usual cause of precipitation—viz., the cooling of a vapour-laden atmosphere. A thunderstorm is caused by the meeting of winds from different sources, one warm and moist and the other dry and cold. These may meet laterally, or there may be an overturning of the atmosphere whei: they suddenly meet above. The latter idea is theoretically the nearest approach to what is sought by advocates of explosions as a means of causing rain to fall. The sudden conversion of a solid explosive substance into gases, perhaps 1,500 times greater in volume, is accompanied by tremendous expansion, force, and heat. This would drive the air about in every direction, and until diffusion of the gases took place would create a state of atmospheric instability, condensation first taking place aloft, then possibly drops falling and introducing a cooler current around, which might cause local showers, such as fall during thunderstorms from the cumulus or anvil shaped clouds caused by " unstable equilibrium." For such effect, I watched most carefully, but in this direction the explosions had apparently no more effect on the vast expanse of the air than would the striking of a match in a room. The forces arrayed against artificial changes in the atmosphere are tremendous —almost beyond conception. A unit" of heat is the amount needed to raise the temperature of a pound of water 1° Fahr., but about a thousand units are needed to transform a pound of water into a pound of vapour. When.vappur turns to water, latent heat is liberated in a corresponding amount. Now, an inch of rain corresponds to 22,635 gallons, or 101 tons 3 qr. 261b., of water to the acre, or over 64,640 tons to the square mile. The heat developed or released under such conditions of condensation from vapour to water for an inch of rain to the square mile is estimated as equivalent to the work done by 100,000,000-horse power for half an hour. Consider again the sweep of a wind, five hundred miles across horizontally, and three miles high, blowing for an hour at the rate of twenty miles. The force of the mightiest explosion with all its gas put forth into the air-is in comparison less than a drop in a bucket. Firstly and lastly, rainfall is concerned with temperature in its relation to the aqueous vapour. Air at different temperatures will hold different quantities of water-vapour, which is an invisible gas, and lighter than the air itself. For example, at 8° Fahr. 2 cubic feet of air will sustain 22 grains weight of vapour, at 60° the same measure would hold lligr., but at 32° only 4| gr. Any additional moisture would be condensed at those temperatures, or a lowering of the temperature would have the same effect —namely, condensation. At ordinary temperatures the capacity of the air for vapour is doubled for every 18° Fahr. Cooling the air by mixture of a cold upper current with a lower warm and vapour-laden one, the meeting of tropical and polar winds in circulating storms, a warm and moist air impinging on a cold surface, would condense the vapour into dew, fog, rain, or snow; and, on the contrary, a warm surface would evaporate water by the conduction of the heat from the ground. Until it can be shown that the temperature of the air can be controlled by gigantic cooling operations, we may look in vain for any alteration in the natural and well-established order of events by way of the production of artificial rain. In ancient times, and long before European settlement, trees seem to have flourished in the Oamaru district, for I am told that big roots are still found in the soil; but, except around the homestead, the country is now very bare of trees. Around their homes the settlers have mostly planted pines, which have flourished wonderfully ; but if larger and more varied plantations were made, particularly in belts intercepting the north-west and south-west winds, though they might not increase the rainfall, yet the trees would not only act as shelters and windbreaks, but also conserve the rainfall which now occasionally runs off in floods. Where possible, the planting of deep-rooting rather than surface-rooting trees of a deciduous kind would bring up water from the lower water-tables, and not only prevent surface evaporation by the winds, but also, as the trees transpire freely in the summer, would create a beneficial humidity in their neighbourhood. The