164 OIL FIELDS OF TEXAS-LOUISIANA COASTAL PLAIN, [bull. 212. 
of the grate bars through an area a little greater than that of the 
aggregate cross section of the tiles. 
A checkerwork (P, fig. 11) of about 50 loose fire brick was built 
over the grates, the space back of the bridge was filled with ashes 
(R, fig. 11) flush with the top of the bridge wall, and a single-course 
floor (Q, fig. 11) of fire brick laid over the ashes. 
An iron bar (a, fig. 10) was bridged across the middle of the fire- 
door opening, and the remainder of the latter closed with fire brick 
(V, figs. 10 and 4) flared on the inside, a small opening (L, fig. 10) 
being left for applying the torch to the burners. Into the iron bar 
across each door was screwed the burner (K, fig. 11). 
Oil enters the burner vertically through the opening (b, PI. VIII) 
under control of the cock (c, PL VIII), regulated by the handle (d, PL 
VIII, A and B.) 
Fig. 11.— Boiler furnace arranged for burning oil. 
Steam enters the opening (e, PL VIII, A and B) and flows through 
the conical opening (f), regulated by the hand wheel (g), to meet the 
oil as the latter falls between the vertical flanges (h, B). 
A third opening (i, A and B) in the burner draws air from the 
back of the furnace through a fire-brick duct built on top of the 
grate and connecting with the bottom side of the latter at its rear, 
while the front end communicates with the iron pipe (M, fig. 10) con- 
nected to both burners. 
A mixture of steam, oil, and heated air is therefore blown out of 
the burner, and this is joined by the main current of air flowing up 
around the front end of the grate bars, somewhat heated by its passage 
along the under side of the grate. 
The oil was stored in an iron tank (A, fig. 10), 7 feet in diamete 
by 5 feet deep, sunk in the ground, into which the oil is emptie 
