shock ceasing, the balls would instantly resume their places Fig 1. in the centre of the cups. This arrangement seems par Fig. 2. ticularly suitable for the purpose in view for the following reasons: 1st. As the balls, supporting the structure, are contained ་ in hollow cups, it must, from the action of gravity, occupy, when at rest, the exact position in which it has been originally placed. 2d. If disturbance of the foundation takes place, and the cups between it and the superstructure are moved, the action of gravity will again restore them and the superincumbent mass to their original normal position. 3d. The sphericity of the balls, and the curvilinear contour of the cups in which they work, render their action. horizontally quaquaversal, and therefore equally efficient from whatever direction the earthquake movement may assail the building. 4th. The simultaneous movement of the balls secures the maintenance of the level, or horizontality of the super structure. 5th. The proposed remedy is simple, and can be applied to any building in which timber or iron beams can be introduced. 6th. While it can be employed on a large scale to the foundations of houses, or of lighthouse towers, it may be employed with equal advantage, on a smaller scale, to any article within a house, or to the apparatus in a light room. In order to prove the aseismatic action of the proposed arrangement, before finally recommending its adoption, we had an aseismatic table, 8 feet in diameter, made at Messrs Milne's works, which was fully tested by actual experiment. It was found that lighted apparatus, when placed on the aseismatic table, was undisturbed by oft-repeated blows from a heavy weight, which when made to strike the table without the aseismatic appliance, instantly capsized and extinguished the lamp. The result, indeed, of the trials made with the table itself, and with models, was perfectly satisfactory, and proved not only that the arrangement neutralises the effects of shocks acting in a horizontal or oblique direction, but that the table is aseismatic, even when tilted up at one side, and thrown off its level. This is the most severe test that can be applied, as any body resting on the table is subjected to the double disturbing action of the shock itself, combined with the table being thrown off the level. The balls, however, neutralise the shock, as in the case of the lateral or oblique stroke. After various trials, the best form of cup was found to be that which is formed with a flat curve towards the centre, gradually increasing in quickness towards the circumference of the basin. It was also found that bell-metal is the best material of which to form the cups and balls. It is obvious that by increasing the number of joints between the upper and lower tables, the aseismatic action of the apparatus could be increased, but the experiments have satisfactorily proved that one joint only is necessary for the lighthouse apparatus designed for Japan. The tables have been formed with snugs of iron on the ribs, for the application of bands of gutta-percha, or any elastic material, and provision was also made for applying a tie-bar, with adjusting springs between the centre of the upper table and the lightroom floor, to provide against any purely upward motion; but it is not believed that any such appliance will, in practice, be found requisite. For the towers, it is proposed to adopt plate-iron, and to give them the form of the frustum of a cone; and to place the whole on balls in the manner already described for the apparatus. The apparatus which has been recommended is the holophotal reflector, which affords certain advantages in its being less easily injured than the ordinary dioptric apparatus illuminated by one mechanical lamp. It has also been recommended that, where any choice exists, sites should be selected where the ground is of as open a character as possible, a rock foundation being, perhaps, the most inappropriate that can be chosen. have also suggested that foundations for towers should be made of masonry set dry without the use of mortar or cement. I The inhabitants of Japan are, as may well be supposed, not insensible to the dangers of earthquake shocks, nor have they neglected means for obviating, to some extent, their effects. Dr Dickson, who has been for some time in the country, has given me much interesting information as to their buildings, and has shown me several native books; and also sketches by himself, which contain much useful information. Japanese buildings generally rest on upright posts or pillars, which are rounded at the bottom, and rest on a foundation of masonry; a joint is thus formed, the continuity of the structure is broken, and by this arrangement the Japanese have made an approach to what I proposed to do more perfectly by the balls and cups. In their books of carpentry, the Japanese also show that the joinings of the uprights and cross-pieces are not made by means of nails or bolts, but by dovetailing and wedging, which admits of adjustment after being disturbed by the wrench of an earthquake shock. The plan proposed has been sanctioned by the Board of Trade, and is now being executed. It is not very easy to realise the importance of such an appliance, which in a country like Japan may be of use in all architectural designs, and even household arrangements. But we may have some notion of its value for lighthouses if we consider for a moment what disasters would happen if all the sea-lights on the eastern coast of our country, between the Thames and the Moray Firth, were suddenly extinguished at the commencement of a dark winter night. We know that in 1799, when the shipping trade was small compared to what it now is, no fewer than 72 vessels were wrecked and stranded in endeavouring to reach the shelter of the Forth, at a time when no light marked the Bell-Rock or other prominent dangers of the coast; and if our lights were now subject to sudden extinction, a similar result would happen in an aggravated form. Extract from a Report by JOHN LESSELS, Esq., Architect, CHARLES JOPP, Esq., Civil Engineer, and Professor CHARLES PIAZZI SMYTH, Astronomer Royal for Scotland, a Committee of the Royal Scottish Society of Arts appointed to consider the foregoing paper. Your Committee having carefully read the above paper, experimented with a model, seen a full-sized example in progress, and heard additional details from Mr Stevenson himself, have come unanimously to a very favourable opinion on both the originality, the efficiency, and the merits of the invention. Mr Stevenson's idea is simply to make the completest possible solution of continuity between any building and the ground it stands upon.. Your Committee consider that this is the true principle to be followed: and that it has been well carried out by Mr Stevenson, especially in his lighthouse arrangements for the earthquake-vexed coast of Japan; and although they cannot undertake to say that the method may not be overmatched some day, by a more than usually terrific earthquake, with both vertical and vorticose movements, and opening clefts in the solid ground, yet they confidently expect that it will mitigate the force of all, and annihilate the action of most of the ordinary shocks. Note of a Cheap and Effective Way of Obscuring Window By R. M. Two years ago the late lamented Sir David Brewster read a paper before the Royal Society, in which he described the use of ground glass in deflecting light into rooms illuminated by a small portion of the sky. He proposed to bring the framework of the window flush with the outside of the wall and to fill it with ground glass, the ground face being outwards. In this way no shadow would be cast by the masonry above the window on the top panes, and the light in its passage downwards through the glass would be arrested by the infinitude of facets introduced by the grinding, and sent inwards and upwards, as well as downwards, *Read before the Society on 13th April 1868, and awarded the Society's Silver Medal. |