357 



have been useful, but the addition of magnetism doubled the 

 efficacy while greatly diminishing the cost, a single layer of 

 wire being quite adequate to the office, and was, in fact, quite a 

 stroke of genius. 



The value of this invention is at once shown by the many 

 complaints which the workmen made when the Respirator 

 was first introduced. They complained that the apertures of 

 the Respirator became so choked that they could not breathe. 

 This was perfectly true, but the complaint showed the real 

 value of the instrument. 



It was necessary for the workmen, every now and then, to 

 clear off the innumerable particles of steel which adhered to the 



SPIRACLE OF FLY. RESPIRATOR OF FORK-GRINDER. 



magnetised wires, and impeded respiration. But they never 

 seemed to realise the fact that, if it had not been for these 

 wires, all the particles would have been drawn into the lungs, 

 and gradually choked them up, brought on inflammation, and 

 extinguished their life altogether. And, with the usual 

 repugnance to new ideas which is inherent in undeveloped 

 minds, the men stoutly resisted the introduction of the 

 Respirator, and did their best to reject an invention which 

 doubled the length of their lives, and enabled them to find 

 long happiness in the world instead of brief pleasure ended by 

 sure and painful death. 



Now, we will see how the principle of the Respirator is 

 carried out in Nature. 



On the left hand of the illustration is drawn one of the most 

 perfect Respirators, or air-filters, if we may use the term, that 

 can be imagined. Perhaps some of my readers may know that 

 insects do not breathe as we do. They have no lungs, but their 

 entire system is permeated by air-vessels, just as is our system 



