Controversy respecting Safety-lamps. 351 



fire-ciamp, and said, " My experiments are going on siicce*5sfiilly, 

 and 1 hope in a few days to send you an account of them. I 

 ai'i going to be fortunate far bevond my expectation." 



la a letter, dated i.Oth of October 1815, he says " I have al- 

 ready discovered that explosive nrixtures of mine damp will not 

 pass through small apertures or tubes^ and that if a lamp or 

 lantborn be made air-tie,ht on the sides and furnished with aper- 

 tures to admit the air, it will not comniunicate flame to the out- 

 ward atmosphere." 



On the 2.1th of October he announced his discoveries to the 

 Chemical Chib of London ; but he soon " gave up the idea of a 

 safety-lamp dependent upon a diminished circulation of air, be- 

 cause lie found that apertures in the top and bottom only, u-ere 

 not safe, unless made so small as to occasion a great loss of light 

 in the flame: i. e. l-5()ih or l-60th of an inch ; and he adopted 

 tubes and canals ahovt and below, uhich proved to be safe br 

 direct ex})erin«nt." In a letter datorl October 30, he describes 

 a lamp of this kind, and has the following reasoning upon it: 

 *' Atmospheric air, wlien rendered impure by the combustion of a 

 candle, but in which the candle will still burn, will not explode 

 the gas from the mines ; and when a lamp or candle is made to 

 burn in a close vessel, having apertures only above and below, 

 an explosive mixture of gas merely enlarges the light, and gra- 

 dually extinguishes it without explosion. Again, the gas mixed 

 in any proportion with oonnnon air^ I have discovered will not 

 explode in a .small tube, the diameter of which is less than l-8th 

 <»f an inch, or even a larger tube, if there is a mechanical force 

 urging the gas through the tube." Some manuscript copies of 

 this letter were taken by professional men of this neighbourhood 

 on the 2d of Noveml)er ; and on the Gth of that month I read it 

 ti» a general meeting of tlie coal trade. 



On the 4th of November, Mr. Butler, in an oration delivered 

 at the foundation of tlie Colloge of tlie London Institution, no- 

 ticed the discovery in the following mauTier: — "At the instant 

 1 am now speaking science is advancing towards us with an in- 

 vention wliich to the latest po-^erity will prove incalculably be- 

 neficial to humanity in general and commerce in particular. 

 You have read in your newspapers of the horrid effects of the 

 firing of a mine. A very recent paper has given an account of 

 auch a disaster. Now within these few weeks, one of those men, 

 homines cenlenarii, as Scaliger called them, who exist but once 

 in a century, men who elevate the country in which they were 

 born, and even the age in which they live, our ilhistrious country- 

 man, Sir H. Davy, has discovered a process by which this evil 

 principle in nature is absolutely .subdued, and 'all possibility of 

 danger from it altogether removed." 



Th.' 



