74 MASSACHUSETTS HORTICULTURAL SOCIETY. 



an iron bench frame with wooden bottoms, these bottoms being 

 easily replaced at a small cost, without disturbing the main 

 supporting frame. If a permanent bottom is desired, porous tiles 

 may be used, which make a practically indestructible bottom, and 

 one which is very beneficial to the plants, as it admits of a free 

 drainage and circulation of air to the roots. For benches or 

 tables in conservatories for the reception of plants in pots, a slate 

 bottom is desirable, the slate being three-quarters of an inch thick, 

 and planed smooth on both sides. This gives ample strength to 

 support large plants. 



I think I have covered the general details in connection with 

 greenhouse construction, as fully as the time will admit, but if 

 there are any especial features which anyone present may wish 

 advice upon, I shall be pleased to give it to the best of m}"^ ability. 



Discussion. 



Kenneth Fiulayson spoke of the difficulty of keeping paint from 

 mildewing in greenhouses, especially tropical houses where there 

 is always so much moisture — a condition that seems to favor the 

 rapid growth of the gray fungus. He asked if there were any 

 known preventive or remedy. 



Mr. Gibbons advised in preparing the paint to use about 

 twenty to twenty-five per cent of oxide of zinc with seventy-five 

 to eight}' per cent of lead. When in Washington some time 

 ago, he visited the conservatory at the White House, and also 

 other structures of the National Government, and was struck by 

 the intense whiteness of the interiors after five to seven years' use. 

 Upon inquiry he was told of this composition, which is found to 

 prevent the growth of the gray fungi referred to, and also the 

 peeling of the paint from the wood. 



In reply to another question, Mr. Gibbons said the Hitchings 

 gutters are of thin cast iron ; the side next to the greenhouse is 

 exposed to the interior heat, which prevents any freezing on that 

 side, even in zero weather ; joints are lapped a little and lined 

 with cement, and all the bolt and screw holes are drilled a little 

 larger than the diameter of the bolts or screws used. By these 

 means all trouble from ice expansion in the gutters is prevented. 



As to lapping or butting glass, Mr. Gibbons thought that 

 lapping is always best. In butting glass it is desirable, if not 

 imperative, tiiat the glass should be of uniform thickness, a con- 

 dition rarely found in either a small or large purchase of glass. 



