HEATING BY HOT WATER. 185 
necessitates placing the chimney near the front of the 
boiler, instead of at the back, and as in this case one 
of the flues must be taken over the top of boiler, this 
one will probably not draw as well as the other shorter 
one. Or the two flues may be joined again, and taken 
back over the top of the boiler to a chimney at the 
back, but this would render a very high chimney 
necessary, especially in the case of a long boiler. The 
Gold Medal boiler will heat from 500ft. to 3,000ft. of 
4in. piping. 
Both the ordinary saddle and the terminal end and flued 
boilers are occasionally constructed with an opening in the 
crown so as to be fed from the 
top. This saves labour to a 
certain extent, and enables the 
furnace to be filled more fully 
than in the ordinary way, through : 
a fire-door in front. Fig. 196. 
A form of saddle boiler known 
as the [-ended was a good deal in vogue at one time, 
but is now almost obsolete. It consists of a small 
saddle boiler of the usual form, connected by means 
of three short tubes—one from the crown and two 
at the back, at the bottom—with a large flat [-shaped 
water-way hood, 4in. or so in thickness, against which 
the flames and heat from the fire act directly and with 
great power. This boiler is consequently very rapid in 
action, as well as powerful, when carefully set, but it 
does not appear to last for any length of time. 
The Trentham, or Cornish boiler (Fig. 126), is a 
powerful type, suitable for heating large quantities of 
