34 



that it may be opened ta admit fresh air as well as to allow the 

 vitiated air to pass away. Another style is to have the base 

 made of terra cotta^ planting the Ferns in this and covering 

 with a glass globe. An improvement has been made in this 

 style, the globes used are chiefly from Fraiiee, and cost from 

 two to five dollars each. They have been liable to break at any 

 time from the fact that the heat inside expanded the glass; the 

 colder atmosphere outside would not allow this expansion; the 

 result was the globe broke. This difficulty has been obviated 

 by having a ventilator put in the top of the globe, this pre- 

 vents breakage of the glass from atmospheric variations, and 

 also allows a current of air to pass through the Fernery at all 

 times. 



