SAFETY-LAMPS. 197 



Other flashing lights, quickly succeeding the first, re- 

 moved their apprehensions and roused their curiosity. They 

 soon discovered whence the light came, and at once turned 

 the suggested learning to account. A bright saw, though 

 not a bad reflector, was inferior in this respect to a mirror. 

 A mirror, therefore, being procured, a man was placed at the 

 mouth of the shaft to hold it, and reflect sunbeams straight 

 down the shaft, as the carpenter had done before. 



The device succeeded well ; sufficient light was furnished 

 in this way to admit of repairs being effected at the bottom 

 of the shaft. The expedient having been thus far successful, 

 those in charge of the mine tried whether, by other reflectors 

 placed within the mine, the sunbeam might not be bent right 

 and left through the horizontal galleries. One angular re- 

 flection could be managed sufficiently well to throw a pencil 

 of light upon a nail-head, or any small object ; but the light 

 was wanting in diffusiveness, and beyond one angular bend 

 the sunbeam could not be made to turn, without incurring 

 such loss of brilliancy that it was no longer of any use. 



Thus not only was the idea of mine-illumination by re- 

 flected light suggested, but turned to useful account. Mr. 

 Goldsworthy Gurney proposed the illumination of whole 

 mines by reflected light not sun-light, for that is both un- 

 certain and difficult to focus. He suggested the employment 

 either of lime for oxy-hydrogen light, or, when a fainter de- 

 gree of illumination might be sufficient, the Bude-light. This 

 gentleman believed it possible to illuminate an entire coal- 

 mine without taking a flame down into it. Artificial light 

 may be produced so intense, that, when placed in the focus 

 of a parabolic reflector, it will throw a shadow eleven miles. 

 He would have the source of light at the mouth of the shaft, 

 and consequently in the open air. A parabolic reflector would 

 be necessary for giving the light its first bend, but after- 

 wards common reflectors would suffice. Of course, whether 

 one source of light should be used, or more than one, must 



