A HARD-WORKING DIET. 351 



out as different compounds, are based upon careful 

 observations and calculations. 



By such methods as these mentioned above we know 

 the sum total of the C, H, O and N that is given off 

 under different amounts of exercise or exertion. 



If the amounts given off in 24 hours are greater The materials 



are sometimes 



than those taken in; if for example the amount of < stored." 

 carbonic acid given off is greater than can be 

 accounted for by the oxidation of carbon taken in, 

 then it is evident there has been a demand made on 

 what has been previously stored up in the body. It 

 is well known that people store up fat who habitually 

 take more carbon and hydrogen than the body 

 actually demands for the work they do, and often 

 store it up to an extent inconvenient to themselves. 

 And the reverse of this is also known, that additional 

 exertion without increase of carbon and hydrogen 

 leads to a reduction of fat, and that a total amount of 

 food inadequate to meet the daily demands, so uses 

 up the stores, that emaciation follows. 



It has been found that the harder the work a man Carbon used 

 does the more carbonic acid he gives off in his breath, 

 which means that more Carbon has been oxidized. The 

 Oxygen comes freely in the air, the Carbon has to be 

 taken in as food. When a man is doing a spell of hard 

 work he should therefore have a care he is taking in 

 more Carbon than when he is doing light work. Those 

 who are continually doing hard work need more 

 than those doing light work. These are facts that 

 do not rest simply on the experiments and calcula- 

 tions of men of science, but have been found true 

 by navvies. Two well-known instances are those of 

 making a railway in Sicily and the laying of the 



