At 2.30pm on Wednesday, March 23rd, 1887, an explosion in the Bulli
mine claimed the lives of eighty one men and boys. The eighty one
bodies were recovered and subsequently buried at St. Augustines
Church of England (where this cache is situated), with eight at
Fairy Meadow Roman Catholic cemetery (Corrimal), some at Woonona
churchyard and the unidentified at Bulli.
There was a sole survivor, Herbert Cope, who was blown out of
the tunnel mouth unconscious. Herbert died in 1952, aged 84.

Bulli Colliery was a "gassy" pit having high concentrations of
"firedamp" (methane) within its coal. Bleeding off into the mine
workings, this gas was diluted and removed to the surface by the
circulating air of the ventilation system before it accumulated and
formed an inflammable mix. The source of the explosion was in the
"Hill End" headings, known to be gassy and subject to gas
"blowers". Not helped by the fact that the men working these
headings had become casual towards the presence of gas and
compounded by a deputy who apparently tolerated the use of unlocked
lamps in contravention of "The Coal Fields Regulation Act",
regulations that required all gas to be reported immediately to
management and that locked oil flame safety lamps be used in gassy
mines. Although oil flame safety lamps were in use at the time, it
apparently was common practice to remove the safety gauze from
around the flame to permit more light from the lamp as this was the
miners' only light source. In addition shots were being initiated
by lighting the fuse from the open flame of the lamp or by
matches.
The cache
At the given co-ordinates you will find an obelisk that was
erected by the government of NSW to the memory of those killed.
On the South side of the obelisk record the names of the two
related men that are twelfth and thirteenth down the list.
Then proceed to S 34 19.988 E 150 54.950 and find the graves of
these two men. You will need to proceed north from the obelisk
through the gate to find them.
To calculate the final co-ordinates, let A= the age of the first
miner mentioned on the headstone and let B= the age of the second
miner mentioned on the headstone. From the grave co-ordinates
(Stage 2) add (A+1)/4 to the South decimals and subtract (B+2)/2
from the East decimals.