In a message dated 22/07/2005, royb1@........... writes:

Doug,
For a "ground-pinger": make a fitting to attach a  bicycle pump to the 
screw cap on a large plastic (one liter?) soda-pop  bottle.  Bury the 
bottle down to the neck (or deeper) and pump until  the bottle fails.  (I 
don't know how much pressure these things will  stand.)
Hi Bob,  
 
    You could fit a car tyre type valve into the  cap and use a foot pump. I 
suspect that the bursting point will be quite  temperature sensitive. It might 
be OK to pump it up to 100 psi or more and then  jab the bottle with a knife 
on a long handle? 

This scheme meets your criteria except the "multiple  impact" and 
possibly the "ping instead of thump" but it's hard to beat for  cheap.
A glass bottle might be more ping-like but would leave  a hazardous 
residue. 
    That would need an awful lot of pressure and flying  glass is very 
dangeous.

Another scheme:introduce a standard spark plug into a  pop-bottle just 
below the neck.  Run two wires (thru a rubber stopper  in the neck or a 
screw cap) into the bottom of the bottle into an inch or  so of water.....
    Umm? How about put 1/2" of water in the bottom, a  couple of wires in 
through the cap, add a teaspoonful of calcium carbide, shake  and wait a few 
minutes. Stand well clear and put a spark between the wires  to fire the gas 
mixture?

 
    This sort of device is used in agricultural bird  scarers and they 
produce a bang which can be heard for a mile or so. It might  well be possible to 
adapt one for seismology?
 
    Alternatively, equip your self with some balloons,  fill them with 
acetylene + oxygen and apply a glowing fuse or cigarette? I  suggest setting the gas 
torch burning with the correct flame shape, wipe  out the flame and then fill 
the balloon? A local school kid did this  with one of the 3 ft weather 
balloons in is father's garage many years ago.  He removed all the nearby windows 
for about 100 yards.....
 
    Regards,
 
    Chris Chapman





In a message dated 22/07/2005, royb1@........... writes:
<=
FONT=20
  style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20
  size=3D2>Doug,
   For a "ground-pinger": make a fitting to at=
tach a=20
  bicycle pump to the 
screw cap on a large plastic (one liter?) soda-pop=
=20
  bottle.  Bury the 
bottle down to the neck (or deeper) and pump un=
til=20
  the bottle fails.  (I 
don't know how much pressure these things w=
ill=20
  stand.)
Hi Bob,  
 
    You could fit a car tyre type valve into t=
he=20
cap and use a foot pump. I suspect that the bursting point will be quite=20
temperature sensitive. It might be OK to pump it up to 100 psi or more and t=
hen=20
jab the bottle with a knife on a long handle? 
<=
FONT=20
  style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20
  size=3D2>   This scheme meets your criteria except the "multiple=
=20
  impact" and 
possibly the "ping instead of thump" but it's hard to beat=
 for=20
  cheap.
   A glass bottle might be more ping-like but would le=
ave=20
  a hazardous 
residue. 
    That would need an awful lot of pressure and fl=
ying=20
glass is very dangeous.
<=
FONT=20
  style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20
  size=3D2>   Another scheme:introduce a standard spark plug into=20=
a=20
  pop-bottle just 
below the neck.  Run two wires (thru a rubber sto=
pper=20
  in the neck or a 
screw cap) into the bottom of the bottle into an inch=
 or=20
  so of water.....
    Umm? How about put 1/2" of water in the bottom,=
 a=20
couple of wires in through the cap, add a teaspoonful of calcium carbide, sh=
ake=20
and wait a few minutes. Stand well clear and put a spark between the wi=
res=20
to fire the gas mixture?

 
    This sort of device is used in agricultural bir=
d=20
scarers and they produce a bang which can be heard for a mile or so. It migh=
t=20
well be possible to adapt one for seismology?
 
    Alternatively, equip your self with some balloo=
ns,=20
fill them with acetylene + oxygen and apply a glowing fuse or cigarette? I=20
suggest setting the gas torch burning with the correct flame shape, wip=
e=20
out the flame and then fill the balloon? A local school kid did this=20
with one of the 3 ft weather balloons in is father's garage many years=20=
ago.=20
He removed all the nearby windows for about 100 yards.....
 
    Regards,
 
    Chris Chapman