268 



THE WALTONIAN CASE. 



obtained ; but as the chief use of the Waltonian case is to 

 raise seeds and strike cuttings, a partial admission of light 

 is usually sufficient. 



The Waltonian case may be made of larger or smaller 

 size. The following figure shows a case of larger size, 

 made on the close principle, by which all is entirely hidden. 

 X shows the door for the introduction of the lamp. 



FIG. 4. 



The interior arrangement of the case may appear some- 

 what complicated, especially the arrangement of the double 

 boiler. We therefore give the accompanying illustration, 

 showing the interior workings. 



A represents the boiler ; B, the steam chimney, opening 

 into the middle of the case, through the zinc tray ; C G C, 

 the zinc tray ; D D D, outer cover to boiler, through which 

 the heat is conveyed from the lamp round the boiler, and 



