296 CULTURE OF THE GRAPE. 



roof, at the same angle with it, and suspended about a 

 foot from the glass. The form of the cane and of the 

 side-branches is represented in fig. 42. It will be seen, 

 that, with the exception of the elevation of the cane to 

 correspond with the pitch of the roof, the form is a very 

 near approach to the horizontal system previously sug- 

 gested. The branches are spread to receive the utmost 

 effect of the sun's light and heat. However this form 

 may -prove to be adapted for open-air culture, there is no 

 question of its excellence for the grapery. Ample venti- 

 lation is necessary ; and, in houses exceeding fifty feet in 

 length, it is best, in addition to the top-sashes and end- 

 doors, to have side-passages for the air to enter. It is 

 better to make large provision for the outlet of the hot 

 air at the top, depending upon the side ventilators as lit- 

 tle as possible for the admission of a cold current at the 

 bottom. For top-ventilation, the simplest form is to hinge 

 sashes about three feet in length to the ridge-pole, allow- 

 ing them to shut down upon the roof like a trap-door. 

 An iron rod a half-inch in diameter, running the length 

 of the house just under the lower lids of the ventilators, 

 will be of sufficient strength to raise them all at once. 

 Pieces of window-cord about six feet in length are at- 

 tached to this rod at suitable distances, which, passing 



