Rainfall in London.
Mr. G. V. Vernon has communicated to the Literary and Philosophical Society of Manchester a Paper on the number of Days on which Rain falls annually in London, from observations made during the fifty-six years, 1807-1862. Howard’s Climate of London has been used for the years 1807 to 1831; the Philosophical Transactions for the years 1832 to 1840; and the Greenwich Observations for the years 1841 to 1862. During the entire period of fifty-six years, no month occurred in which rain did not fall.
The minimum number of days occurred in 1832, the cholera year, and 1834; the number of days being 86, 82 respectively. The maximum number occurred in 1848, the number being 223 days.
Taking the quarterly values, we find that rain falls on the greatest number of days in autumn, and the least in spring.
Taking the means of five yearly periods, there appears to be a kind of periodicity in the number of days on which rain falls; having a maximum in 1815 to 1817, and a minimum in 1845 to 1847.
The Force of Lightning.
A person may be killed by Lightning, although the explosion takes place at the distance of twenty miles, by what is called the back-stroke. Suppose that the two extremities of a cloud, highly charged with electricity, hang down towards the earth, they will repel the electricity from the earth’s surface, if it be of the same kind with their own, and will attract the other kind; and if a discharge should suddenly take place at one end of the cloud, the equilibrium will instantly be restored by a flash at that point of the earth which is under the other. Though the back-stroke is often sufficiently powerful to destroy life, it is never so terrible in its effects as the direct shot, which is frequently of inconceivable intensity. Instances have occurred in which large masses of iron and stone, and even many feet of a stone wall, have been conveyed to a considerable distance by a stroke of lightning. Rocks and the tops of mountains often bear the marks of fusion from its action, and occasionally vitreous tubes, descending many feet into banks of sand, mark the path of the electric fluid. Some years ago, Dr. Fielder exhibited several of these fulgorites in London, of considerable length, which had been dug out of the sandy plains of Silesia and Eastern Prussia. One found at Paderborn was forty feet long. Their ramifications generally terminate in pools or springs of water below the sand, which are supposed to determine the course of the electric fluid. No doubt the soil and substrata must influence its direction, since it is found by experience that places which have been struck by lightning are often struck again. A school-house in Lammer-Muir, in East Lothian, has been struck three different times.—Mrs. Somerville’s Connexion of the Sciences.
The inquiries into the chances of refuge from lightning have been attended with saving results. Here is an instance:
A few years since an awful thunderstorm occurred in the neighbourhood of Inkpen, Berkshire. Three men, named Martin, Buxey, and Palmer, were employed in mowing grass, when a storm of thunder and lightning broke over the field, and one of them suggested that they should run beneath a tree; Martin knowing that trees generally attract lightning, immediately remarked, “We had better go anywhere than under a tree.” Buxey and Palmer, however, as the storm was severe, and the hail was falling heavily at the time, ran and seated themselves beneath a large lime-tree, but Martin walked off to a cottage, and was safely sheltered. In about half-an-hour after the storm had abated, both Buxey and Palmer were found lying on the grass beneath the tree, quite dead from the lightning. The clothes of Buxey were found to be on fire, and the hair of Palmer was much scorched.