620 
and an eighth diameter, but both orifices being of the same 
area as that of the round one. 
BOILER PRESSURE 281bs. PER INCH. 
AREA OF EACH JET 4-10THS OF AN INCH. 
Description of Jet. 
Velocity of air in 
wood pipes per 
minute, in feet. 
Quantity of air 
discharged per 
minute, in feet. 
1,100 
1,650 
1,320 
1,980 
1,500 
2,250 
BOILER PRESSURE 401bs. PER INCH. 
1,330 
1,995 
1,600 
2,400 
1,810 
2,715 
The steam was supplied from a Cornish boiler of about 
twenty horses nominal power, but no steps were taken to 
ascertain the exact consumption of fuel, or the quantity of 
water evaporated. The firing, however, was such as to 
shew that the jet with twenty-eight pounds pressure, absorbed 
about half as much steam as the boiler was able to produce, 
and with forty pounds pressure, about three-fourths ; and the 
consumption of fuel would probably be one and a half 
hundred weights, and two hundred weights respectively 
per hour. 
On referring to the above tabular statement it will be 
observed that although the jets have the same area of 
aperture, they show different results ; that of the annular jet 
being better than the round one, and the large annular jet 
still better than the smaller one. It was not ascertained to 
what extent the enlargement of the jet could be advan- 
tageously carried, but the size named gave a decided 
advantage. The annular orifice can be increased or 
diminished in area by simply turning round the internal 
cone, at the bottom of which a screw is formed for the 
convenience of adjustment. 
