ON LOADING PUNT-GUNS 213 
and in each charge a varying strength is usually found. Hold 
to the fine gunpowder ; it is most reliable. 
-It should be almost unnecessary to mention that tubes, 
caps, etc., for igniting the big gun must be kept as dry as 
possible when afloat. Nothing beats a glass bottle tightly 
corked in which to keep these articles. Ordinary matches 
should likewise be kept in a similar vessel, or else, if carried 
loose or in chip match-boxes in the pocket, they are very liable 
to become damp, or even wet and useless. A further protection 
against damp affecting matches is to half fill the bottle they 
are to be kept in with bran or sawdust—the latter for preference. 
A leathern cover should be strapped around the breech of all 
punt-guns, so as to protect this part of the gun from wet. 
We intended to give full details of an electrical ignition for 
punt-guns, so that this method might be employed aboard 
motor-propelled craft. But we have conclusively proved by 
experiment that there is no advantage whatever to be gained 
by using an electric spark for this purpose, even where all the 
apparatus is at hand. We much prefer percussion ignition, 
for reasons too numerous to mention here. We have, however, 
made lengthy experiments on this subject, and can say we 
attained equally good results as with the customary methods 
of ignition, yet no better, and we must add, with not half the 
confidence in the result. The chief drawback is the insulating 
qualities of the priming powder in the firing cartridge or tube, 
offering a high resistance against the spark. Our tests were 
made entirely with B.L. guns. Ordinary induction or sparking 
coils similar to those used on motor-cars are almost useless for 
firing gunpowder, as the resistance of the powder against a 
spark appears to be many times greater than explosive gases, 
even under compression. At least two 4-volt accumulators 
coupled up in series are necessary for the primary circuit of the 
coil. The electrical potential difference at the point of sparking 
must be of very high voltage to strike through the powder 
