POLYTECHXIC ASSOCIATION PROCEEDINGS. 645 



may be elevated on a wall, or placed on smooth solid basis of con- 

 crete. The water-troughing constitutes the roof plate. The roof 

 dips into and rests on this plate, and consequently removes the 

 water condensed on the internal surface of the glass, as well as the 

 rain from the outside. The upright supporting pillars are hollow 

 tubes, which can be stopped at pleasure, or used in the conduction 

 of rain water into tanks, according to the plan firet introduced by 

 Mr. Bogardus, of New York, the inventor of the cast-iron house. 

 A ventilator, worked by an endless screw, extends the whole length 

 on the top of the house, and is set at a greater pitch than the 

 remainder of the roof. It opens outward on each side, thus form- 

 ing a double ventilator. A series of balanced ventilators are placed 

 on each side near the base of the building, through which air is 

 admitted. The glass is inserted into a T shaped iron rib, and ou 

 each side of the edge of the glass is placed a strip of asphated felt, 

 which is held in its place and made tight hy a plate and screws. 

 This arrangement supersedes the use of putty. The iron is not 

 painted, but is covered with a flux, which is baked on before the 

 pieces are put together, thus forming a durable enamel. This 

 structure is comparatively cheap, and not liable to need many 

 repairs. 



CRANBERRY BEDS. 



The production of the cranberry in Ejistern New Jersey is worthy 

 of remark. In Ocean c^junty alone the cultivated cranberiy beds 

 cover an area of more than one thousand acres. The most approved 

 plan of making a bed is to select a bog or low piece of ground, 

 which can be easily flowed with water and drained to the depth of 

 two feet, and after turning under the sod and pulverizing the sur- 

 face, to cover the whole with white sand to the depth of six inches. 

 The plants are placed about eighteen inches apart. They must be- 

 kept clear of weeds, and in the course of three or four years the- 

 whole surface will be cohered with the vine. By means of a dam,, 

 the bed is kept under water about one-half of the year; this plaii 

 effectually checks the ravages of the worm. The crop may be 

 gathered in the fall, or if covered bv water durinsr the winter, ia 

 the spring. The average jaeld per acre in New Jersey is aljout 

 one hundred bushels, and the average price per bushel about three 

 dollars. After the bed begins to bear, the production of the berry 

 is attended with less care and trouble than any other crop. Unl ike- 

 other berries, it can be preserved without difficulty for a long time; 

 the market, too, is seldom over-supplied. Large qnanties are n^efl 



