15 
The suggestion thrown out by Mr. Baxendell at our last 
meeting — that the explosive effect of lightning is due to 
the conversion of moisture into steam — seemed to me to be 
so very probable that I was induced to try if I could not 
produce a similar effect experimentally. 
1. I first of all tried to burst a thin slip of wood by dis- 
charging a jar through it, taking care so to arrange the 
wood that the discharge should be of the nature of a spark 
and not a continuous discharge ; this was done by making 
the wood to form part of a discharging rod with balls on 
the ends. 
This experiment was successful in the first attempt, 
although the results were on a small scale. 
It should be mentioned that the wood had been damped 
with water. 
This experiment was repeated with larger pieces of wood 
with various results. 
2. It then occurred to me to try with a glass tube. This 
I did at first wdth a very small tube, passing wires from 
the ends of the tube until they were within ^ inch of each 
other. 
The small tubes burst both with and without water. 
3. I then used a larger tube (about iV inch bore), using it 
in a similar manner. The discharge without water pro- 
duced no effect on this, even when repeated several times, 
but when the tube was full of water (with the ends open) 
the first discharge shattered that part of the tube opposite 
the gap in the wire. This tube was bent in the form of a 
syphon, and the water stood about 1 inch beyond the gap 
in the wire on each side of it. 
4. I then tried a stronger tube which I had been using 
for insulation. It had a bore of ^ inch and was f inch 
in external diameter. It was capable of sustaining a pres- 
sure of probably 10,000, and certainly 5,000 lbs. on the 
square inch, that is to say, a pressure of from 2 to 5 tons 
