PRELIMINARY REMARKS. 



141 



must have been in use towards the end 

 of the fifteenth or beginning of the 

 sixteenth century, for at that period 

 their gardens contained many of the 

 plants of the East Indies. The system is 

 still very generally met with throughout 

 Holland and the Netherlands, although 

 many instances occur of more modern 

 methods being adopted. It consisted of 

 the common stove of the country, placed 

 at one end of the hothouse, inside, the 

 smoke and heated air being carried along 

 the middle or front in earthenware tubes 

 about 10 inches in diameter, and smaller 

 at one end than at the other, so as to 

 admit the end of the one entering that of 

 the next, the joints being secured with 

 soft clay or cement. This method was 

 also in use in this country, only with the 

 improvement of having the fire placed 

 outside the house, and burning in a small 

 furnace similar to those used at present 

 for heating wash-house boilers. 



Another mode of heating then adopted 

 on the Continent, and in some places 

 still continued, was by a small iron 

 waggon mounted on wheels, and filled 

 with burning charcoal, which was drawn 

 backwards and forwards through the 

 house in severe weather. Strange as it 

 may appear to many, such an apparatus 

 was, not long ago, in use in the Botanic 

 Garden at Oxford, and was in all proba- 

 bility introduced by Bobart, a German, 

 who was the first curator in that garden. 



These earthenware or can flues have 

 been improved by using well-prepared 

 fire-clay instead of common brick earth, 

 which makes them much stronger and 

 more durable, and at the same time their 

 form is changed to the spigot and faucet 

 joint, by which means they are rendered 

 more secure. A still farther improvement 

 has taken place by making them square, 

 egg-shaped, and rounded at top. 



Another mode of heating was and 

 still is employed on the Continent, for 

 warming orangeries and large plants- 

 houses, consisting of a common iron 

 stove placed within the house, the smoke 

 and heated air being conducted through 

 iron pipes suspended from the roof or 

 otherwise, as circumstances may direct. 

 This is the most dangerous mode of 

 heating imaginable, and ought to be 

 entirely exploded. — (See section, Hot-air 

 Stoves.) 



Brick flues constituted the next step 

 towards an improved mode of heating, 

 and those first used in this country were 

 merely drains built under ground. These 

 were followed by the broad and deep 

 flues of the Dutch, built on the surface, 

 but not separated from it. These are 

 in very general use still throughout 

 France and the Netherlands, and almost 

 exclusively so in Russia and the north of 

 Germany. About the same period, flues 

 were built in the solid walls in this 

 country, and placed in the front, or more 

 generally in the back wall of the house. 

 The obvious defects of these modes of 

 heating require no comment. 



The detached brick flue was adopted 

 in this country about the end of the last 

 century, and, under different modifica- 

 tions, still continues in pretty general 

 use. These, if well built and properly 

 managed, have their advantages. They 

 are less expensive and more quickly 

 heated than steam or hot-water pipes, 

 and therefore useful in repelling sudden 

 attacks of frost in plant-pits and green- 

 houses. The space they occupy and 

 their heavy appearance militate against 

 their being used in greenhouses of the 

 first order, unless they are placed under 

 the stages or plant-tables, as in figs. 133 

 and 134, or under the floor, as in fig. 135, 

 in which latter case they should be 



Fig. 133. 



Fig. 134. 



Fig. 135. 



