GENERAL REMABES ON HEATING. 149 
is not in use; and (3) the risk of the flame getting too 
high and smoking. When this occurs the whole of the 
interior of the structure, with its contents, become covered 
with a greasy soot, which is at once very unsightly, 
injurious, and difficult of removal. 
In all cases these stoves must be kept scrupulously 
clean, oil of the best quality only being employed, and 
if carefully trimmed and not allowed to burn too high, 
a well-made stove may be used without any injurious 
effects, and indeed, with fairly satisfactory results. 
But nothing beyond thoroughly excluding frost must be 
attempted, and the stove be only used when actually 
necessary, that is to say, when the thermometer outside 
falls below about 36 degrees Fahr. Air should also be 
freely admitted whenever possible, in order to allow of 
the speedy escape of any fumes, and get rid of the 
unpleasant odour. The improved and superior makes 
of these stoves, however, give off little or no smell, and 
these only should be used, avoiding the common or cheap 
kinds. Although thus useful, in careful hands, for smal 
structures where only a low temperature is required, these 
stoves are entirely inadmissible for heating large houses, 
or for anything of the nature of forcing. In some cases 
it is found advisable to place a pan of water on the top 
of the stove, when burning, but in others the combustion 
alone produces quite sufficient moisture in the atmosphere, 
and occasionally rather too much. 
But decidedly the best and least objectionable form of 
oil or gas-stove (without hot water pipes) are those , 
constructed on the ‘‘radiator’” principle, as it is called, 
one of which is shown in Fig. 97. In these it will be 
