86 MASSACHUSETTS HORTICUIiTURAL SOCIETY. 



approach to it was in tlie couservatory at tlie Botanic Garden at 

 the Capitol in Washington. That house was originally built 

 entirely of iron, the glass being set directly on the iron rabbets. 

 In this form it was not a success, and after repeated repairs and 

 modifications, wood rabbets for the glass were substituted, and in 

 this modified form it has since been fairly successful. The 

 experience of Superintendent Smith with this house and his 

 valuable suggestions led the way to a decided and important 

 improvement. During the winter of 1880-1881, Mr.. Gould's 

 extensive range of glass and collection of plants were entirely 

 destroyed by fire, caused by a defective flue. The old houses were 

 of wood construction, and Mr. Gould requested that if possible 

 the new ones should be of iron. Up to that date there were no 

 greenhouse builders in this country using iron for construction, so 

 that to meet Mr. Gould's desire, it became necessary to plan a new 

 dei)arture in the method of construction. With the experience of 

 the Botanic Garden in mind, the new details were perfected and 

 successfully embraced in rebuilding Mr. Gould's houses, and were 

 almost innnediately adopted Ijy the late Peter Henderson in an 

 extensive range for commercial jiurposes. With such endorse- 

 ments the new method of construction soon became popular, and 

 most of the important glass buildings erected since that time have 

 been built on substantially the same plans. The winter garden 

 and greenhouse of William B. Forbes at Milton was one of the 

 earliest examples of this style of construction in the vicinity of 

 Boston. The system admits of any form of roof which may be 

 desired, from a plain and simple lean-to, to a large, full span, 

 curvilinear structure, with Gothic or ogee curves. In curvilinear 

 work it has entirely superseded the former wood construction. 



The iron sill is cast in sections of the same length as the 

 distance from centre to centre of rafters, usually six to eight feet 

 long, and shaped to cap an eight or twelve inch wall, according to 

 the size of the building. A lug is attached by a tap bolt to the 

 end of each sill ; the rafter is placed so that it rests partly on the 

 end of each sill, and when a single bolt is placed through both 

 lugs it will be seen that the two pieces of sill and rafter are all 

 substantially secured. The exi)ansion of the sills is allowed for 

 in a very simple manner by drilling the lioles in the lugs slightly 

 larger than the tap bolts. The form of the sill is sucli that great 

 strengtli is obtained with the use of but a few pounds of metal 



