308 Chronicles of Science. [April, 



entered in safety, with the advantage of having a sufficient light for 

 examination. It must not be thought that anything approaching to the 

 brilliancy of the electric light proper is obtainable. When the ex- 

 cited coil is brought in connection, by means of wires, with the Geiseler 

 tube, into the ends of which pieces of platinum wire are hermetically 

 sealed, it is filled with a rich phosphorescent glow, resembling in its 

 nature the auroral light. 



The weight of the apparatus, — the inconvenience which must ever 

 arise from the use of a voltaic battery, with its two fluids, — the pre- 

 cautions necessary to ensure the perfect action of the induction coil, — 

 and the delicacy of the Geiseler tube, are difficulties in the way of this 

 lamp, which must prevent its use under the ordinary conditions of 

 colliery labour ; but there are extraordinary cases constantly arising in 

 our " fiery " collieries, in which it may be advantageous to introduce 

 this lamp so ingeniously arranged by Dumas and Benoit. The Insti- 

 tute of France has given the inventors " an encouragement " of 1,000 

 francs for this application of electricity, stating its advantages to be, 

 that it afforded the means of giving succour to miners in danger of 

 perishing from the effects of fire-damp or of the " after-damp." 



M. Alphonso Dumas attended a meeting of the North of England 

 Institute of Mining Engineers on Saturday the 4th of February, to 

 exhibit his lamp. The light was said to cost one penny for ten work- 

 ing hours. The President said the inventor had no idea of his lamp 

 superseding the Davy lamp ; but merely hoped that it might be useful 

 in places of extreme danger. Mr. Easton said the principle of a phos- 

 phoric light was not entirely new. He had heard of stale fish having 

 been used for the purpose. 



Mr. Samuel Plimsoll, a gentleman connected with the South York- 

 shire coal trade and that of London, has communicated to Dr. Allen, 

 of the Philosophical Society of Sheffield, and Mr. Peacock, the Secre- 

 tary of the Coal Owners' Association, his ideas on certain plans by 

 which he supposed the presence of carburetted hydrogen may always 

 be visibly indicated to the miner in the galleries of any colliery. 

 From Mr. Plimsoll's statement, which includes many subjects having 

 but small relation to Fire Damp, we gather, that he supposes the light 

 carburetted hydrogen of the coal mines to exist only in the upper parts 

 of the galleries ; therefore, he would have a tube open at both ends, 

 protected from currents by boxes. In this he would place a small 

 balloon of gold-beater's skin, filled with the lighter gas — this bag 

 would float on the common air, but would not rise into the carburetted 

 hydrogen — and thus he conceives there would be a regular indicator 

 of the quantity of gas in any place where the tube might be placed. 

 This apparatus is so simple, that there can be no difficulty in trying 

 the experiment. We fear Mr. Plimsoll has entirely forgotten the law 

 of the diffusion of gases, which is often very rapid in its operation ; 

 but we shall hear more of this if it proves of any value. Mr. 

 Plimsoll proposes also the application of some chemical means to 

 register the presence of fire-damp. We heartily desire that he may 

 be successful in his efforts to discover a safe and easy plan for deter- 

 mining this question, and then direct his attention to the improvement 



