202 Miscellanies. 



2. Safety of steam boilers. — By a Royal Ordinance in France of 

 March 27, 1830, it is decreed that every boiler employed in public 

 works or manufactories, where steam is equal to two atmospheres and 

 over : shall have 



1. Two safety valves of equal dimensions, and each of sufficient 

 size to discharge the steam freely in case of its too great tension. 



2. Each valve shall be loaded by direct pressure, and without the 



intervention of a lever with a weight equivalent, at most, to one at- 

 mosphere. 



3. Near one of the valves on the top of the boiler, there shall be 

 adapted a metallic plug, fusible at the temperature of 127° centigrade 



(=260.6° Fahr.). This plug shall be of such a diameter that its 



free surface shall be four times as great as that of one of the safety 

 valves. 



4. One of the valves and the fusible plug shall be locked up under 

 the same grated enclosure, and the key shall remain in the hands of 

 the principal of the establishment. The other valve shall be under 

 the direction of the engineer of the machine. 



5. Each boiler shall be furnished with a manometer open to the 

 air, the glass tube of which shall terminate at the height of twenty 

 eight inches (French) above the level of the mercurial surface press- 

 ed by the vapor.— Bull. D'Encour. AvriL 1830. 



3. 



yf the Mecanique Celeste, by N. 



We perceive in this translation, (says the Revue Encyclopedique,) 

 an incontestable proof of the progress of mathematics in the United 

 States, a country which we are accustomed to consider as sterile in 

 the sciences which are purely speculative. If all the divisions of hu- 

 man knowledge are there cultivated with as much success as this, 

 earning will flow back towards its origin, and the west will shed its 

 light upon the east. As the second volume of this translation is to ap- 

 pear in the course of the present year, we shall reserve our account of 

 both until it arrives, and this will impose upon us new mathematical 

 studies, for the indefatigable translator has more than doubled the ex- 

 tent of the original by his notes and commentaries, which will be more 

 particularly the objects of our attention.— Rev. Encyc. Mai, 1830. 



4. Germination upon mercury.— M. J. Pinot read to the Acad- 

 emy of Sciences, of Paris, a memoir, in which he certifies that a 

 gram ol Latfynu odatm, after being steeped in water, was placed 



