New York Agricultural Experiment Station. 291 



lliat flie blocts be so placed that wben the door is forced into 

 position it will almost but not quite reach the metal supports 

 at the bottomj This will admit of some wear before the door 

 is down as far as it will go. 



As shown in the illustrations, four strips are required. The 

 upper one should be placed at the top of the door so as to press 

 the two surfaces of felt as close together as possible, thus lessen- 

 ing the possibility of leakage of gas. To make the pressure on 

 the upper part of the door as great as possible the upper strip 

 should be warped somewhat and then sprung into place. 



nf preferred metal lugs may be cast, together with correspond- 

 ing supports, and used in place of the strips and blocks. The 

 principal advantage over the wooden fasteners would be that 

 thev would wear longer. 



To put the door in place it is only necessary to lift it so that 

 the ends of the cross strips may drop into the fasteners. Ks 

 own weight will bring it nearly into place, and it will require 

 but little additional force to drive it down as far as necessary. 

 The handling of the door will be facilitated if the surfaces of the 

 fasteners coming together are lubricated. 



The principal advantage of this fastener over the old is the 

 case and speed with which it permits the door to be put into 

 place. It takes but a very few seconds. No ladder is required 

 and the delay and consequent expense of turning each button 

 into place is avoided. The door is held in place as securely as 

 with the buttons, and we have found by careful tests that with 

 the new fasteners there is no more danger of leakage of gas 

 than before. 



'See Bulletin 181, page 139. 



