close under the glass, and resting on the borders. The arrangement may be understood from the subjoined diagram.
![](http://upload.wikimedia.org/wikipedia/commons/thumb/9/9a/Arrangement_of_pipes-Amateurs_Greenhouse_Conservatory-0049.jpg/329px-Arrangement_of_pipes-Amateurs_Greenhouse_Conservatory-0049.jpg)
ARRANGEMENT OF PIPES IN EXAMPLE OF HEATING ON THE LEVEL.
A. Entrance to lean-to. B. Entrance to Paxtonian. C. Boiler.
D. Flow. E. E. Return. F. Forcing-pit.
The solution of a difficulty in this simple way is a matter of more than passing interest, for where it appeared impossible to employ a hot-water system it has been effectually accomplished, and a most excellent forcing-pit obtained into the bargain. It is an important exemplification of established principles that the lean-to which adjoins the boiler, and receives its pipes directly from it, obtains far less heat than the Paxtonian, which is twenty-five feet distant, and the pipes which