146 Royal Academy of Sciences of Paris. 



M. Bory-de-Saint- Vincent continued the reading of his 

 Memoir on the Physical Geography of Spain. 



M. Dupetit-Thouars commenced the reading of a Memoir on 

 the Differences between Monocotyledones and Dicotyledones. 



M. de la Borne, after having presented some new experi- 

 ments on Voltaic electricity, stated that his results would be 

 found in the sealed packet presented by him on the 10th of 

 March. 



Report on Steam Engines. 



M. Dupin read the conclusions of the Report made by him 

 in the name of a Commission, consisting of MM. Laplace, 

 Prony, Ampere, Giraud, and Dupin, on the use of low and 

 High Pressure Steam Engines, considered particularly with a 

 view to the public safety. M. Gay-Lussac, whose opinion on the 

 subject differed in many respects from those adopted in the Re- 

 port, had requested to withdraw from the Commission. The 

 conclusions adopted by a majority of the Academy were as 

 follows : 



" 1 . Two safety valves to be adapted to the boiler. One of 

 them to be so disposed as to remain out of the reach of the 

 workman who attends the boiler and the working of the engine ; 

 the other to be placed under his controul, in order that as oc- 

 casion may require he may be able to lessen the pressure ; 

 whilst he would be unable to increase this pressure, as the 

 valve to which he has no access would give vent to the steam 

 at a lower pressure than that at which he might imprudently 

 aim. 



" 2. We propose that the strength of every boiler should 

 be proved by means of the hydraulic press, submitting it to a 

 pressure four or five times greater than that which it would 

 have to sustain in the usual work of the engine, so long as the 

 pressure is between two and four atmosphei-es; and that above 

 this term, the pressure in proving should be as many times 

 greater than the usual pressure exerted by the steam in the 

 work of the engine, as that pressure exceeds the simple pres- 

 sure of the atmosphere. 



" 3. We propose that every manufacturer of steam-engines 

 should be obliged to make known his method of proving, and 

 every thing which can ensure the strength and safety of the 

 engine, especially of the boiler and its appendages. The 

 manufacturer to be obliged to make known to the authorities 

 as well as to the public, the usual pressure at which the engines 

 should be worked. 



" 4. The boilers of steam-engines in the neighbourhood of any 

 habitation to be surrounded by a wall, in every case where the 

 explosion would be sufficient to throw down the partition-wall 



between 



