164 The Trials of Suction Gas Plants at Derby , 1906. 
and thence to a channel surrounding the top of the vaporiser, 
whence it drips on to the ribs in succession and is gradually 
vaporised. The air inlet is marked on Fig. 2 and the air is 
preheated in by means of the hot gases, through the inter- 
mediary of a spiral rib EF cast on to the gas pipe, before 
coming in contact with the water vapour, as will readily be 
seen from the figure. 
Fig. 3. — National Gas Engine Co., Ltd. General arrangement of Engine and Producer Plant. 
Producer of Messrs. Crossley Br6s., Ltd. 
The producer submitted by Messrs. Crossley Bros, is shown 
in Figs. 4 and 5, pp. 165 and 166. 
The special feature in this producer is the disconnection 
between the bottom of the firebrick lining and the grate, the 
object of which is to minimise, if not prevent, the formation of 
clinker on the firebrick. The trials at Derby confirmed this 
contention ; not a vestige of clinker was ever found on the 
firebrick. The tubes of square section shown in the figure are 
airducts and intercept the radiant heat and thus warm the air 
supply. It will be noticed that the firebrick lining is continued 
at a larger diameter above the level of the glowing fuel, and 
surrounds the vaporiser, which is a specially shaped steel 
open-mouthed vessel enclosing the lower part of the storage 
bell. This steel vaporiser can be easily removed for cleaning 
or renewal. The air inlet for what is called by the makers the 
“primary air,” is placed on the top cover ; the air is heated by 
contact with the hot surfaces, and after taking up moisture 
, from the vaporiser is drawn through the square section tubes at 
