320 
POPULAR SCIENCE REVIEW. 
opening up, or disintegration) of the material composing the tube through 
which detonation is transmitted, generally appears to exert no important 
influence upon the result obtained. At any rate, the differences with respect 
to smoothness of the interior of the tubes far outweigh those which may 
prove traceable to differences in the nature of the materials composing 
them. 
A Patent Feeder and Grate for Consumption of Fuel , which has been 
recently exhibited by Messrs. Frisbu, appears to be a most ingenious 
arrangement for feeding a lire with coal from the bottom. This feeder and 
grate provides a simple method of feeding fuel up, from underneath the fire, 
into all descriptions of furnaces, fuel-boxes and fire-grates. By this prin- 
ciple of feeding from below the fire there is no fresh consumption of the 
fuel, the igniting of the fresh coal is a gradual process, while at the same 
time a very intense heat is obtained. The hottest portion of the fire being 
constantly at the top utilises the heat, and preserves the fire-bars from 
being burnt out ; the heat of the surface of the fire is not abated by the 
supply of fresh fuel, and no cold air is admitted to the furnace while feed- 
ing, thereby preserving a perfectly uniform heat. By feeding from beneath, 
the coal is pushed up and outwards equally from the centre of the grate, 
and is evenly consumed, with scarcely any refuse except fine ashes, which 
drop down through the grate-bars without raking. From various testi- 
monials which the inventor has received, it seems that there is a great 
saving in the use of the coal ; thus one firm says their coal bill averaged 
160/. a month, but on introducing one of these burners they only used that 
quantity in four months. 
A TJsefid Saving Form of Fire-grate . — The invention of the Rev. J. 
Wolstencroft is described as follows in the u Chemical News.” The 
inventor says the great difficulty is solved, viz. 11 how to get a healthy, 
cheerful fire, imparting a genial heat, with half the amount of fuel com- 
monly used.” We (says the Editor) saw the grate in use, and we must 
candidly admit it was the most cheerful and the brightest fire in the 
place, but as to the amount of coal it daily consumed we are unable to say. 
According to some experiments which have been performed with it by James 
D. Curtis, Commander Royal Navy, there is truth in the inventor’s state- 
ment that there is a great economy in the consumption of fuel. Captain Cur- 
tis, of Brimpsfield, Gloucester, experimented with the grate in his harness- 
room from August 18, 1873, to September 1, 1873, using no other fire, burning 
slack coal delivered for 24s. per ton, employing this fire daily for cooking 
small things, such as boiling potatoes for the fowls, &c., and after the 
daily use the fire was left to burn itself out during the night ; the cost 
of coal per day was 3 hd. The front of the grate is continued down to the 
floor, cutting off the supply of air from within the room ; by this means an 
air chamber is formed under the grate, to which the air is communicated 
from within or without the building, bringing the draught under and 
directly through the fire-bars. In a fire-grate which has been fitted up in 
Manchester, at the office of one of the Local Boards, the air-chamber com- 
municates with the main sewer, and draws its supply from thence — thus, as 
it is supposed, ventilating the sewer, at the same time consuming the 
noxious sewer gases. Any kind of fuel can be used, and very small coal 
