1918.] The N.Z. Journal of Science and Technology. 223 
damaged, and because of the consequent hazard due to possible earthing 
or short circuit. 
Passing now from the ordinary wiring of an installation, I will take 
some of the apparatus used in a household. Easily the first favourite is 
the electric pressing-iron, of which a fair estimate of the number in use in 
the Dominion at the present time is anything between twenty-five and 
thirty thousand. Its convenience and simplicity of operation appeal to 
the average housewife, and are also appreciated in many clothing-factories. 
It is, however, a most serious fire hazard, and until a “ fool-proof " electric 
iron is placed on the market that hazard will remain. There is, of course, 
a fire hazard in the gas-heated iron, or the common sad-iron; but in 
the latter case the heat is gradually diminishing once the iron is removed 
from the heating-arrangement, and in the former there is more or less of 
a reminder with the gas. With the electric the source of heat is not visible, 
and there is absolutely nothing about the iron which will indicate that it 
is being heated. If only the person operating the iron would remember to 
open the switch and thereby cut off the current all would be well ; but, 
unfortunately, in many instances this simple action is neglected, the iron 
is left standing on the ironing-cloth or table, and in due course a fire is 
started. 
The temperature of an iron for safe and satisfactory use is from 400° 
to 600° F. This temperature is not dangerous, but when the irons are 
allowed, after using, to remain with the current on continuously their 
temperature rapidly increases to 1,200°, 1,400°, or even to 1,600° F., and 
the iron may become red-hot. Naturally, under such conditions any 
combustible material in contact with it will ignite. I know of many 
instances where severe losses have occurred due to the electric iron. 
Metal stands are sometimes supplied with the iron, but that does not 
eliminate the hazard, although it reduces it. Another idea was to put a 
lamp in series with the iron, so that the lamp would always be burning 
when the current was on. That was not a success, because when the lamp 
burnt out it was often short-circuited instead of being replaced with a 
new one. In fact, short-circuiting was often adopted to save the current 
in the lamp. 
The next step was to have a small pilot lamp wired in parallel with the 
iron, and often fixed behind a red bull’s-eye. The objection to this is that 
if the lamp burns out it need not be renewed, because it is in parallel with 
the iron, and, in spite of the red light burning, people often leave the ironing- 
table without switching off the current. 
One manufacturing firm turned out an automatic iron whereby the plug 
connection was thrown out when the temperature reached a certain degree. 
To replace the plug a trigger had to be pushed down with a screw-driver 
or similar instrument; but this resetting was so often done in such a clumsy 
way that many irons were ruined, and as that particular make was getting 
a bad name, and all through sheer clumsiness, the makers withdrew them 
from the market. This was regrettable, as one of this make has been in 
constant use for the past eight years in the writer’s house and has never 
given the slightest trouble, and never been out for repairs. It has often 
thrown out the plug, due to a high temperature, but there has been no 
trouble in the resetting again. 
Another hazard of the iron—and this also applies to radiators, kettles, 
cookers, and similar devices consuming a heavy current—is in operating 
