124 THE WONDERFUL HOUSE THAT JACK HAS 



of course, most essential to have plenty of pure air 

 in the schoolroom, for in it numerous pairs of lungs 

 must be supplied with oxygen five or more hours a 

 day. The vitality of many people may no doubt be 

 lessened by the impure air in churches and other large 

 assembly halls, and troublesome and even dangerous 

 diseases may be contracted as a result. The possi- 

 bility of serious injury, however, is not nearly as great 

 as in schoolrooms, because the sessions are shorter 

 and much less frequent. 



Can it be proved that people have really been 

 injured by breathing impure air? Two often quoted 

 events establish this fact beyond a doubt. In the 

 year 1756, the Nawab of Bengal, having attacked the 

 employees of the East India Company in Calcutta, 

 made prisoners of one hundred forty-six. At eight 

 o'clock in the evening these prisoners were confined 

 in a room twenty feet square, having two small win- 

 dows. Soon their sufferings began to be terrible. 

 They fought for places near the windows, trampled 

 one another under foot, and even begged the guards 

 to shoot. At two o'clock in the morning but fifty 

 were living, and at daybreak, only twenty-three. 

 Ever since that terrible night this dungeon has been 

 known as "The Black Hole of Calcutta." As there 

 were two windows, a few persons might have survived, 

 even in that hot climate, but the supply of air was 

 far too small for the number of prisoners confined. 



Some years ago the steamer Londonderry, which 



