Steam Engines. 203 



The royal printing office, which employs 80 presses, 295 

 workmen, and from 70 to 80,000 reams of paper, is not in- 

 cluded in this estimate. 



Of the books printed annually in France, it is estimated 

 that there are of theological works seven per cent., of juris- 

 prudence five, arts and sciences twenty, politics sixteen, 

 belles-lettres twenty-eight, and'history twenty-four, — Bulletin 

 des Sciences, Geographiques, Statistigues, (^c, Mars ISSi. 



on 



51. Rapid evaporation. — Professor Oersted has pointed 

 uut a method of considerable utility in the evaporation of 

 liquids. He fastens together a great number of tine metallic 

 rods, or wire, and puts them in the bottom of the distillery 

 or evaporating vessel, and by this means he distils seven 

 measures of brandy with the same fuel, which without the 

 rods would distil only four. — Bidlelin des Sciences, Physiques, 

 4-c. Avril, 1 824. 



52. Steam Engines. — The French Institute have subjected 

 to a careful investigation, the various circumstances connect- 

 ed with the explosion of steam boilers, and an ordinance of 

 the king, founded most probably upon the conclusions of the 

 Academy, decrees : 1st. That no high pressure engine shall 

 be established without a license. 2d. That every proprietor 

 shall declare before the proper authority, the degree of pres- 

 sure with which his machine is intended habitually to act. 

 3d. That no high pressure engine shall be erected without 

 having its strength previously determined by the hydraulic 

 press, that every boiler shall be able to sustain five times the 

 force under which it is to act, that the intended pressure shall 

 be stamped upon it, and that no boiler shall be erected until it 

 receive this stamp. 4th. That two safety valves shall be 

 adapted to each boiler, so large that either of them can dis- 

 engage the steam with sufficient rapidity, one of them to be 

 at the disposal of the fire man, and the other covered with a 

 grating, locked, and the key kept by the proprietor. 5th. 

 That two round plates shall be inclosed in the boiler, one of 

 which to be at least equal in diameter to the safety valve, 

 and to be composed of a mixture of metals wiiich will melt or 

 soften at a temperature of 10° centigrade, above that of the 

 boiler; the other of double the diameter, inserted near the 

 locked valve, and of such a composition as to soften at 20" 



