20 TEAR-BOOK OP FACTS. 



the pistons in the high pressure cylinders is transmitted to the piston 

 of the low pressure cylinder, and the piston-rod of this cylinder 

 transmits the power of the whole to the crank shaft. By this arrange- 

 ment a compound engine is obtained which does not occupy more 

 space than an engine having a single cylinder of the size of the low 

 pressure cylinder of the compound engine, with the further advantage 

 that the power generated both in the high and low pressure cylinders 

 is communicated to one crank by a single connecting-rod. The slide 

 valves of the high pressure cylinders, and the slide valves of the low 

 pressure cylinders are connected together, and are actuated by one 

 pair of eccentrics and the link motion, as described in the specifica- 

 tion of a previous patent of the present patentee, dated Nov. 10, 

 1858.— Ibid. " 



INCRUSTATIONS IN BOILERS. 



Mr. L. M. Boulard has patented an "Improved Apparatus 

 for Preventing or Destroying Incrustations in Steam Boilers." This 

 consists in the substitution of a mechanical arrangement to the 

 chemical reagents at present in general use for the prevention of cal- 

 careous deposits in steam boilers, or their destruction when formed. 

 This arrangement is composed of a case or bag of pierced steel 

 metal, metallic gauze, or even non-metallic tissue, corresponding in 

 shape witli the boiler, in which it is euclosed, and forming as it were 

 an open worked lining, kept at a slight distance from the inner sur- 

 faces by means of brackets. If so required, this lining, the meshes 

 or perforations of which should be finer at the bottom than at the 

 top, may be made in several sections, which are passed separately 

 into the boiler, by the main hole, and afterwards connected in any 

 suitable way. In many cases the metallic or other tissue may be 

 replaced by a simple recipient in a sheet metal, or even iron metallic 

 material without perforations inserted in the boiler, and secured by 

 brackets as above. In this case the apparatus, instead of being com- 

 pletely tubular, should be of a gutter form open at the top, the end-; 

 being either left open or closed with pierced metal or gauze. Or 

 again, the' B&me results may be obtained by the insertion in the boiler 

 of any required number of wire gauze or other perforated sb 

 superposed at equal distances, and so arranged as to be easily with- 

 drawn from time to time for the removal of the calcareous matters 

 ed. — Mechanics' Magazine. 



Mr. James It. Napier, shipbuilder and engineer, of Glasgow, has 

 submitted to the Philosophical Society of that city a paper "ii the 

 Incrustation of Boilers aaing sea water. We have only space to 

 quote th" following remarks from the conclusion of Mr. Napier's 

 elaborate paper : — 



" Prom the foregoing example," he says, "of a vessel worked at a 

 temperature of 270', it is alao Been that a quantity of tin!, equal to 

 15s per cent, of that which produces evaporation, is consumed by the 



ordinary blowing-off method, in order to prevent cruet, and this 



amount increases with the temperature. Brine chests DATS baa 



