234 Scientific Intelligence. [March, 



The second, or " tube lamp " of Mr. Stephenson, instead of 

 the valve, or slider, and the central passage for the air, has 

 three open tubes on the outside of the flame ; their length is 

 stated to be " 3-i- inches, and their diameter between ^ and ± of 

 an inch : " as no lamp on this construction could be procured, 

 Mr. Newman was directed te make one on the model of that 

 described by the Committee ; but as it was concluded that the 

 three tubes would be insufficient to maintain the combustion, 

 three additional ones were inserted. Notwithstanding which 

 it was found that the lamp was completely incapable of burning, 

 unless it had a chimney so far approaching to the cylindrical 

 form, that the air could pass down it to feed the flame ; a circum- 

 stance which, it is obvious, would render it useless as a safety 

 lamp. 



The third lamp, instead of the valve, or the tubes, had metallic 

 plates, both at its lower part, and at the upper end of the chim- 

 ney, in which were apertures of about £ of an inch in diameter. 

 The identical lamp upon which these experiments were performed, 

 was one that had been made under Mr. Stephenson's inspection, 

 and had been furnished by him to one of the collieries for their 

 use ; in every trial to which it was subjected it was insufficient to 

 prevent explosion. 



The fourth lamp seems to have been regarded by the Com- 

 mittee as not essentially differing from the third ; and it so far 

 resembled it, that it consists of a system of perforated metallic 

 plates. In this, however, the apertures are reduced in size to 

 from -j-L- to T '- of an inch in diameter ; and, by this change, it is 

 rendered incapable of communicating explosion ; so that it may 

 be entitled to the appellation of a safety lamp, so far as this part 

 of its construction is concerned. It has, however, one very 

 serious defect, which must, we conceive, in a great measure, 

 render it inapplicable to the purposes of the miner. It has a 

 cylindrical chimney of thick glass, which is nearly in contact, at 

 its lower part, with the small apertures that surround the wick. 

 When the lamp is exposed to an explosive compound, the small 

 jets of flame that rise up through these apertures produce a 

 degree of heat which must almost unavoidably break the glass ; 

 and this accordingly occurred with the lamp in question. Mr. 

 Stephenson's friends seem to admit that this fourth lamp was not 

 constructed until after Sir H. Davy's most important experiments 

 were made public, and known at Newcastle. 



The results of these experiments must be considered as pecu- 

 liarly important, because they would appear to be very different 

 from those that were obtained by Mr. Stephenson's committee, 

 of which an account is given in their report. 



XII. Prizes proposed hi) the Royal Academy of Sciences for the 

 Years 1818 and 1819. 



The Academy published in 1815, on the subject of a prize in 

 natural philosophy, the following preamble : 



