188 EFFECTS OF DEFICIENT VENTILATION. 



pure air actually occur, is not a matter of doubt. 

 Among other writers, Mr. Thackrah, in his excel- 

 lent little work on the effects of trades and profes- 

 sions on health, expresses himself strongly to this 

 effect, and specially notices that dyspeptic symptoms 

 are often the first indications of the commencing 

 disease, and that the lungs suffer only after the di- 

 gestive system has been for a time disordered. It 

 may not be easy to explain why the stomach and 

 bowels should suffer even sooner than the lungs 

 themselves, from a cause which seems exclusively ' 

 directed to the latter ; but observation substantiates 

 the fact, and it is one of much interest in enabling 

 us to trace to their true sources many of the forms 

 of bad health prevalent in the middle ranks of life. 



Although, however, the first effects are so often 

 referable to the stomach, the lungs and general 

 system sooner or later become implicated. An in- 

 dividual possessing a strong constitution may indeed 

 withstand the bad consequences of occasionally 

 breathing an impure atmosphere, but even he will 

 suffer for the time. He will not experience the 

 same amount of mischief from it as the invalid, but 

 will be perfectly conscious of a temporary feeling 

 of discomfort, the very purpose of which is, like 

 pain from a blow, to impel him to shun the danger, 

 and seek relief in a purer air. The comparative 

 harmlessness of a single exposure is the circum- 

 stance which blinds us to the magnitude of the ul- 

 timate result, and makes us fancy ourselves safe and 

 prudent, when every day is surely though imper- 

 ceptibly adding to the sum of the mischief. But 

 let any one who doubts the importance of this con- 

 dition of health watch the dyspeptic, the pulmonary, 

 or the nervous invalid through a season devoted to 

 attendance on crowded parties and public amuse- 

 ments, and he will find the frequency of headaches, 

 colds, and other fits of illness increase in exact pro- 

 portion to the accumulated exposure, till, at the end 



