iSyi.] Engineering. 545 



such that, if the ship had really possessed it, no pressure of wind upon any 

 extent of sail she could possibly have carried could have forced her over. 

 Upon further reflection, Mr. Ruthven found the official curve of stability to be 

 grossly incorrect, and not even agreeing with the inclining experiment which 

 had been made at Portsmouth in order to ascertain the position of the centre 

 of gravity. The inclining experiment, as stated in evidence, proved that 

 80 tons placed on the deck at 20 feet from the centre line, heeled the ship 

 6 degrees, and this, of course, was the measure of her stability at 6 degrees. 

 This 80 tons multiplied by the 20 feet give 1600 foot-tons as her stability at 

 6 degrees ; while the curve produced in court showed a stability, at 6 degrees, 

 of no less than 2600 foot-tons. The official curve gave 7100 foot-tons as the 

 maximum stability at 21^ degrees, with a stability of 5700 foot-tons at 

 14 degrees, which was retained up to an angle of 31 degrees ; while, in point 

 of fact, the highest real stability of the Captain was only about 3400 foot-tons 

 at 16 degrees, and 3260 at 14 degrees, which she carried only up to 18 degrees. 

 The accompanying diagram shows the difference between the assumed and 

 the real curve of stability of the Captain, as explained by Mr. Ruthven. 



Stone Caissons. — A new application of Ransome's patent concrete stone has 

 recently been introduced by a Mr. Butler, which seems likely to come into 

 extensive use, and to effect a great revolution in the construction of hydraulic 

 works. The object of this invention is to employ cast-stone caissons in the 

 construction of foundations for piers, bridges, river-walls, and all kinds of 

 hydraulic works. The rapidity and ease with which blocks of any form and 

 size can be produced on the spot where they are to be employed, are no small 

 considerations in favour of this new application of Ransome's stone, whilst the 

 materials which form its base are generally found in abundance where hydraulic 

 works are carried on. This application of Mr. Ransome's process has been 

 suggested for two reasons — the first, to provide a cheap and thoroughly 

 efficient substitute for stone for hydraulic works ; and, secondly, to render 

 unnecessary the construction of false works, coffer-dams, &c, and to avoid the 

 employment of iron-cylinders and caissons, now of necessity so extensively 

 used. Experimental tests have shown the Ransome stone to be second only 

 to granite in its powers to resist a crushing force. The strength of granite to 

 resist crushing varies from 8000 to 12,000 lbs. per square inch ; the Ransome 

 stone, 8g6o lbs.; BramleyFall,5i2olbs.; and Portland stone, 2630 lbs. per square 

 inch. In practice, the materials forming the stone will be moulded in situ into 

 blocks, either solid or cellular, of the required shape and dimensions. The 

 cellular blocks form, however, the special peculiarity of this system. For 

 bridge-piers and abutments the blocks may be rectangular or circular, for dock- 

 and river-walls they may be square or hexagonal — in fact, any required shape 

 may be given to them. For convenience in sinking the blocks (an operation 

 which is precisely similar to that employed in sinking iron cylinders) the lower 

 edge of the bottom length would be chamfered, and, when necessary, shod 

 with iron. The horizontal joints would be made preferably with alternate 

 projections and depressions in the sides of the blocks, and the vertical joints 

 are made good with timbers halved into each block. 



Selenitic Mortar. — A most valuable addition to the building arts has recently 

 been invented by Colonel Scott, R.E., of South Kensington, and called by him 

 Selenitic Mortar. The process of production consists in mixing with the 

 water used in the preparation of the mortar, a small quantity of sulphate of 

 lime in the form of either plaster-of-paris or gypsum, or by adding green 

 vitriol. The mixture is prepared in the pan of an ordinary mortar-mill, in 

 which the water and the sulphate are first introduced, and subsequently the 

 lime. After the lime has been ground for three or four minutes, the sand, 

 burnt clay, or other ingredients are added, and the whole are ground for ten 

 minutes more. By this invention, ordinary lime can be at once converted into 

 a species of cement-mortar which sets rapidly and well, and can be used for 

 concrete, bricklayers'-work, or stuff for plastering, at a cheaper rate than that 

 made from lime in the ordinary way. The use of sulphuric acid has been 

 found to give the best results, although sufficient acid is contained in plaster- 

 of-paris to prevent the lime from slaking, which in effect is the secret of the 



