8 PREFACE, 



In the firll brick bed which I had built, a flue 

 was carried length-wife in the middle of each 

 frame, and the hills of mould for the plants to 

 grow in were made upon this flue ; but I was 

 obliged to alter it, becaufe I found the heat, in- 

 troduced through means thereof, too power- 

 ful for the roots of the plants. 



Alfo in the firfl bed I had fix leaden pipes 

 fixed in the frames, one end in the cover- 

 ings of the flues, and which communicated 

 with the fteam of the linings, and the other 

 end going through the north fide of the frames, 

 projecting about a foot beyond them : Thefe 

 pipes were intended to draw the heat out of the 

 flues occafionally. Alfo in each three-light 

 frame in the coverings of the flues I had round 

 holes made here and there, and wooden plugs 

 or fl:oppers fitted for them exadtly. Thefe holes 

 or apertures were to admit the fl:eam of the 

 linings when fweet to enter the frames among 

 the plants ; but thefe, as well as the pipes, I 

 found by experience to be ufelefs, and even in 

 fome refpeds rather hurtful : They are there- 

 fore juftly exploded, which renders a defcrip- 

 tion of their operations at this time altogether 

 unnecefl^ary. 



In the firfl bed too the four-inch thick folid 

 walls between each three-light bed were carried 



up 



