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congeners, the " whalebone," or " baleen," as it is more pro- 

 perly called, is so formed that it allows liquids to pass through 

 it, while it retains solids. Feeding as it does upon small 

 marine matters, it would starve but for the filtering power of 

 the baleen, which enables the animal to take into its vast 

 mouth the sea-water with its inhabitants, and to expel the 

 water through the plates and fibres of the baleen, while retain- 

 ing the animals. 



The process of filtering, as well as the structure of the 

 baleen, is so familiar that it does not need further description. 



WE will now proceed to another filter, which is used in the 

 air, and not in water, namely, the Mouth-guard or Respirator 

 of the fork- grinder. 



There is, perhaps, no trade which is more destructive of 

 human life than that of the fork-grinder was until the peculiar 

 respirator was made obligatory. The minute particles of steel 

 thrown off by the grindstone fills the air, and were necessarily 

 inhaled. Now, the human lungs are capable of enduring very 

 bad treatment, but the introduction of steel-dust into them is 

 more than they can bear. Consequently the duration of human 

 life was very short, consumption almost invariably setting in 

 at an early age, and carrying off the men before they had 

 achieved middle age. 



Nor did the mischief end there. It was bad enough that life 

 should be shortened, but far worse that it should be wasted, as 

 was mostly the case. The men, knowing what their fate must 

 be, were simply reckless, and plunged into all kinds of 

 debauchery, under the plea of " a short life and a merry one." 

 They knew no better, and could scarcely be blamed for their 

 mode of living. And, as a matter of course, each succeeding 

 generation was worse, smaller, and feebler than the preceding. 



Then there came the invention of the Magnetic Respirator, 

 by which the fork-grinder's trade was rendered as healthy as 

 any other. It was made of steel- wire gauze, and magnetised, 

 so that the floating particles of steel were not only stopped in 

 their progress to the lungs, but arrested by the magnetism, and, 

 so to speak, taken prisoners by it. 



Even a well-made respirator of several layers, like those 

 which are used by persons suffering from weak lungs, would 



