82 FERNS IN THEIR HOMES AND OURS. 



recommended for a small house. In the larger 

 establishments near Boston, the Hitchings and 

 Smith & Lynch boilers are most frequently em- 

 ployed. The old-fashioned " saddle-back " boilers 

 are fast disappearing from use. If the chimney is 

 first made to pass through the house in the form 

 of a brick flue, much heat from the smoke is 

 saved ; but the danger of the leakage of the prod- 

 ucts of combustion, which might, in half an hour, 

 allow gases enough to escape to destroy the whole 

 collection,, may be an argument against this econ- 

 omy. It creates the necessity of a constant watch 

 to guard against such a result ; and the few dollars 

 saved are more than balanced by the difficulty, in 

 dull days, of kindling a fire with the draught of so 

 long and crooked a chimney. 



