FORCING DEPARTMENT. 331 



that that which is attended with the least labour 

 and consumption of fuel must always bear the pre- 

 ference. 



The square boilers possess the advantage of simpli- 

 city, and of ready access in getting them cleaned, to 

 prevent an incrustation settling on the inner side of 

 the bottom, which frequently occurs where the sedi- 

 ment of the water is not removed, and which renders 

 the bottom liable to be burned out of them, as the 

 water within is prevented from coming in contact 

 with the part immediately on which the fire plays. 

 When the pipes and boilers cannot be placed on a 

 level, as is sometimes the case, and when the former 

 have to be carried over the door, or to dip under 

 it, it is necessary to have steam-tight boilers for 

 forcing the water along the different levels ; but the 

 reservoir cover should be left unscrewed, in order 

 that a little steam may evaporate out by the edges of 

 the cover, which will prevent any collection or ex- 

 plosion of the steam ; but the less complicated the 

 apparatus is, the more efficacious it will generally be 

 found, as well as the least expensive. 



Since the preceding observations went to press, I 

 have had an opportunity of seeing Mr. Weeks's 

 newly invented boiler, &c. which, in my opinion, is 

 the most economical and complete apparatus for the 

 heating of Hot-Houses, &c. that I have seen. This 

 boiler consists of several hollow bars, or pipes, con- 

 nected together in the shape of an oblong square, 

 which are kept full of water, and form the fur- 

 nace that the fire rests on, that immediately warms 

 2 u 2 



