290 LIGHT SCIENCE FOR LEISURE IIOURS. 



the present century, and the number of deaths result- 

 ing from them, are in reality much more significant 

 than th'ey seem to be at first sight. But even inde- 

 pendently of this consideration, the record of the 

 colliery accidents which took place at that time is 

 sufficiently startling. Seventy-two persons were killed 

 in a colliery at North Biddick at the commencement 

 of the present century. Two explosions in 1805, at 

 Hepburn and Oxclose, left no less that forty -three 

 widows and a hundred and fifty-one children unpro- 

 vided for. In 1808, ninety persons were killed in a 

 coal-pit at Lumley. On May 24, 1812, ninety-one 

 persons were killed by an explosion at Felling Col- 

 liery, near Gateshead. And many more such accidents 

 might readily be enumerated. 



(From the Daily News, December 4, 1868.) 



THE DUST WE HAVE TO BREATHE. 



A MICEOSCOPIST, Mr. Dancer, F. R. A. S., has been 

 examining the dust of our cities. The results are not 

 pleasing. "We had always recognized city dust as a 

 nuisance, and had supposed that it derived the peculiar 

 grittiness and flintiness of its structure from the con- 

 stant macadamizing of city roads. But it now appears 

 that the effects produced by dust, when, as is usual, it 

 fin do its way to our eyes, our nostrils, and our throats, 



