228 On the Construction of Kitchen 



artificial current of air; and to this we may add that 

 the current of air which goes up a chimney, in conse- 

 quence of the combustion of fuel in an open chimney 

 fire-place, is produced in the most expensive and dis- 

 advantageous manner that can well be imagined. It 

 would not be difficult to prove that much less than one 

 thousandth part of the fuel that is necessary to be burned 

 in an open chimney fire-place, in order to cause a smoke- 

 jack to turn a loaded spit, would answer to make the 

 spit go round, were the force evolved in the combustion 

 of the fuel properly directed, through the medium of 

 a steam-engine, for instance. 



But it is not merely the waste of power or of mechan- 

 ical force, that unavoidably attends the use of smoke- 

 jacks, that may be objected to them : they are very 

 inconvenient in many respects ; they frequently render 

 it necessary to make a great fire in the kitchen, when 

 otherwise a great fire would not be wanted ; they very 

 frequently cause chimneys to smoke, and always render 

 a stronger current of air up the chimney necessary than 

 would be so merely for the combustion of the fuel wanted 

 for the purposes of cooking; consequently they increase 

 the currents of cold air from the doors and windows to 

 the fire-place ; and, lastly, they are troublesome, noisy, 

 expensive, frequently out of order, and never do the 

 work they are meant to perform with half so much 

 certainty and precision as it would be done by a com- 

 mon jack, moved by a weight or a spring. 



There is, I know, an objection to common jacks that 

 is well founded, which is, that they require frequent 

 winding up; but for this there is an easy remedy. A 

 jack may without any difficulty (merely by using a 

 greater weight and a greater combination of pulleys) 



