Miscellanies. 185 



It is closed on the top with a moveable cover composed of bricks 

 bound together by an iron band. Several of these furnaces extend 

 along a wall and are connected with a wide chimney. The top ot 

 them is on a level with the floor, and their common ash pit is a cellar 

 about ten feet high. 



The crucibles, of very refractory clay, are sixteen or eighteen 

 inches deep and five inches in diameter. About forty pounds ot 

 steel are melted in them in five hours. In a state of fusion, it fills 

 rather more than half a crucible ; the latter are simply covered with 

 an earthen slab. One of them cannot serve for more than three op- 

 erations. 



No fuel is used but good coke ; that which has been prepared in 

 ovens is preferred. The melted steel is poured into moulds held per- 

 pendicularly, and when full, an iron weight is laid on the top to pre- 

 vent the melted metal from boihng out of the mould, but not so heavy 

 as to increase much its density. — Ann. de Chimie, Tom. VI, 105. 



4. Hydrostatic balance. — Different kinds of apparatus have been 

 invented for demonstrating the hydrostatic paradox of Pascal, viz. 

 that the pressure of fluids is in proportion to their depth, and that at 

 equal depths it is the same whatever may be the form or capacity of 

 the containing vessel. The following arrangement is proposed by 

 De Haldat, in the transactions of the Royal Society of JYancy. 



A simple syphon is inverted, filled with mercury, and one of the 

 branches is enlarged in order to be adapted to different vessels ; and 

 the other branch, more narrow, is provided with an index which 

 shews by the invariableness of the mercurial column, the equal pres- 

 sure upon the common junction of these vessels of unequal capacity. 



5. Hydrostatic press. — In the same volume is descjibed a very 

 simple and cheap and at the same time powerful, hydrostatic press, 

 invented by Debuisson an architect of Nancy. It is composed es- 

 sentially of a large leather bag, in the room of the large cylinder of 

 common hydrostatic presses. This bag, fifteen inches in diameter, 

 is placed in a wooden cyhnder, the sides of which are strengthened 

 by iron bands. The bag, by expanding in this cylisider, presses up- 

 wards a wooden platform on which are placed the materials to be 

 compressed, and wiiich are confined as usual between cross beams 

 strongly jointed in a frame. A lad of twelve or fi teen, can by this 

 machine e.\ert a pvessure of sevenfv to eighty thousand pounds. The 



Vol. XIX,— No. L ' .24 



